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This is geology B with all of us
trampled. the Eon in which we 

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live is called the phanerozoic, 
which comes from the ancient, 

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Greek word, for Visible life, 
the Eon starts with the 

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Cambrian, which began 541 
million years ago, But in recent

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decades, it has become 
increasingly clear from the 

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fossil record that there was 
visible life before the Cambrian

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and complex life at that. 
So what caused it to emerge then

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and what causes it to 
proliferate and diversify so 

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vigorously in the early 
Cambrian, Rachel Wood is 

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Professor of carbonate 
geoscience at the University of 

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Edinburgh. 
She and her team have uncovered 

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fossils that suggests that the 
fuse of the so-called Cambrian 

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explosion was lit in the 
ediacaran. 

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The geological period that 
preceded, the Cambrian Rachel 

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would welcome to geology B. 
Thank you very much. 

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How old is the oldest large 
fossil? 

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Well, the record is quite 
remarkable. 

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We think the origin of life was 
anywhere between about 3.6 and 

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3.8 billion years ago, but the 
oldest large fossils. 

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We have our in rocks, that are 
approximately between 570 and 

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575 million years old. 
And in fact, the oldest examples

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are probably found In Canada, in
Newfoundland. 

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What did these last large 
fossils actually? 

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Look like when they were quite 
unlike anything that we know 

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today, they were remarkably 
large, they could be up to about

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a meter in size and they had a 
very, very unusual organization 

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often a fractal. 
In some cases a fractal 

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organization. 
If you can imagine some of them 

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were like giant sea pens almost 
like giant feathers. 

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They had a stem and a 
feather-like part but they were 

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routed onto the sea floor, 
probably associated with 

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microbial, mats and biofilms. 
When I evoke the image of sea 

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pens is not to say that they 
were remotely related to sea 

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pens but they looked rather like
giant feathers will see pens on 

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the seafloor others lived. 
Horizontally on the sea floor. 

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Again with this fractal 
organization where they 

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preserved because they had hard 
body parts know these oldest. 

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Since we call them had no 
skeletons whatsoever. 

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If they did have some sort of 
skeleton, it might have been an 

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organic skeleton, perhaps of 
something, akin to collagen, or 

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some sort of gel that supported 
their tissues. 

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But they were entirely 
soft-bodied, what sort of rocks.

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Do we find these fossils in? 
Well, the oldest examples are 

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found and what we call clastic 
rocks. 

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So these are shales and 
siltstones, in other words, 

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rocks that are dominated by 
tiny. 

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Grains of quartz and Clay, some 
of the most remarkable settings 

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where these earliest 
communities. 

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These earliest microfossil, 
communities are preserved in 

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situ now actually preserved by 
being buried very very rapidly 

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by turbidity currents. 
And these are very turbulent 

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flows that start in Shallow 
Waters but actually eventually 

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come to rest in very deep water.
So we know that these 

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communities were living in 
remarkably deep bits of the 

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seafloor. 
This bit of juice, Equal time. 

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How can we get precise dates for
the rocks, in which we find 

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these fossils? 
Well, the most powerful and the 

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most accurate method we have for
dating age of fossils is to find

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Ash beds that are associated 
with these Fossil Beds, 

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obviously before or after 
interleaved. 

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If you like, with these Fossil 
Beds and we extract a key 

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mineral called Zircon. 
And Zircon is very, very good 

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for measuring and isotopic ratio
with Ray genic Isotopes, 

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particularly you Uranium, and 
then it's daughter LED. 

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So we can measure this ratio 
between radiogenic, uranium and 

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it's daughter LED and extract a 
pretty accurate date for when 

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these Ash beds full. 
And so we can really bracket 

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where these Ash beds occur, we 
can really bracket the age of 

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these communities. 
Presuming these Precambrian 

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fossil-bearing beds, mostly 
fairly rare an outcrop only in 

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certain places on the planet 
where do we find them then? 

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Well, what's Extraordinary is 
these beds with these 

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communities of soft-bodied 
microbiota. 

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They are remarkably Global so we
find them in Canada, in North 

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America, Siberia, Australia. 
There are remarkable populations

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and Namibia so they are really 
widespread far more widespread 

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than you would expect for the 
preservation of soft-bodied 

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forms. 
Can you speculate us to why they

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might be so ubiquitous It is an 
area really active research 

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because how could something that
might have had the consistency 

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of a jellyfish few. 
Like, how did that get preserved

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in these sediments? 
Where they've simply wouldn't be

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preserved today. 
So, there are several hypotheses

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to evoke the fact that perhaps 
seawater at this time had very, 

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very different chemical 
constituents today. 

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So for example, one set of ideas
proposes that we had elevated 

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00:05:28,400 --> 00:05:32,200
amounts of silica dissolved in 
seawater and this Effectively 

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aided the preservation of these 
by auteurs. 

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00:05:35,500 --> 00:05:38,500
There are other ideas that 
suggests that these microbial 

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00:05:38,500 --> 00:05:40,600
films, which we know they're 
associated with. 

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Might have formed some sort of 
death mask that preserved, these

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forms and indeed other 
hypotheses of voc, the 

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preservation of key clay, 
minerals that again, could have 

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been a mechanism by which the 
claimant was coated, these 

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fossils and then aided 
preservation. 

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00:05:58,600 --> 00:06:03,600
But all these ideas really rely 
on On non uniformitarian 

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principals. 
And other words, the present is 

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not the key to the past, the 
past is a different place. 

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00:06:09,400 --> 00:06:13,600
Things happened differently, 
there you're a field geologist, 

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so you actually go and hunt for 
these fossils in the field. 

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Where have you been to get the 
fossils that you've just been 

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discussing? 
Well, the air is, I've spent 

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most time in the last five years
or so. 

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Have been a Biblia particularly 
in the southern Namibia, but 

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also South East Siberia. 
Yeah, and actually, when the 

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00:06:32,800 --> 00:06:36,600
most remarkable Expeditions I've
been on recently was to a very 

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remote part of South East 
Siberia of the udemy river. 

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It was an area that really 
hadn't been studied extensively 

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since the early 1980s and I was 
very privileged to go with a 

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joint Russian Chinese and UK 
Expedition, we were out in the 

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bush for five weeks with no 
connection to the outside world.

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Living off the land, bear is 
pickled mushrooms. 

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Beautiful, delicious fresh water
fish. 

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We lived like kings, but it was 
a very, very remote existence 

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enjoyable. 
But very challenging, you've 

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mentioned that there were 
probably special conditions that

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prevailed at that time to enable
these soft-bodied creatures to 

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be. 
So are preserved. 

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In the fossil record does that 
information or any other 

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information? 
You've been able to extract from

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the rocks at that time. 
Give you some Clues as to what 

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it was in the environment that 
triggered the emergence of 

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complex life at that particular 
time. 

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Yes. 
I mean but this is a very 

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complex problem the way to try 
and understand why something was

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preserved may or may not be 
related to why the animal if 

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they were animals, they may not 
have been animals. 

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These biota, why would they were
there at all? 

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So you have to think about the 
prerequisites for complex life 

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and very much the flavor of 
research in the last 20 years, 

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or so has been assigned. 
Idea that we needed, sufficient 

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oxygen present dissolved in 
seawater. 

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That would allow the emergence 
of complex life and we know that

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the origin of animals in 
particular, certainly requires 

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some amount of oxygen, exactly. 
How amount of oxygen is very 

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much debated because we now know
that animals with very, very low

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metabolism. 
So for example, sponges which 

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00:08:27,900 --> 00:08:32,000
cannot move they have very few, 
if you You like metabolic 

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00:08:32,000 --> 00:08:35,200
requirements. 
These need much much lower 

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00:08:35,299 --> 00:08:38,799
amounts of dissolved oxygen. 
Then say a predator that 

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00:08:38,799 --> 00:08:43,299
actively boobs and has a 
high-energy lifestyle so there 

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00:08:43,299 --> 00:08:48,000
are all sorts of ideas and 
hypotheses out there that evoke 

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00:08:48,400 --> 00:08:52,200
the the stepwise. 
If you like or perhaps episodic 

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00:08:52,200 --> 00:08:56,000
injection of oxygen as being a 
key, requirement to allow 

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00:08:56,500 --> 00:08:59,500
increasingly more complex life 
with increasingly more 

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00:08:59,800 --> 00:09:03,300
metabolically demanding life, 
Dials in particular, animal 

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00:09:03,300 --> 00:09:07,100
Lifestyles. 
Okay, so is the idea that we 

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00:09:07,100 --> 00:09:12,000
started off with an anoxic or 
largely anoxic planet and 

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00:09:12,100 --> 00:09:16,100
eventually in the late 
ediacaran, the dissolved oxygen 

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00:09:16,100 --> 00:09:20,700
levels reached a critical point 
which enabled complex life to 

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00:09:20,700 --> 00:09:22,700
emerge. 
Yes, that's it. 

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00:09:22,900 --> 00:09:25,800
There isn't a huge amount of 
consensus for these key bits of 

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00:09:25,808 --> 00:09:28,900
geological time, particularly 
the easier car, and the early 

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00:09:28,900 --> 00:09:31,900
Cambrian. 
But If you ask people this 

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00:09:31,900 --> 00:09:35,400
question maybe 20 years ago they
would have suggested two 

156
00:09:35,400 --> 00:09:37,900
episodes of increased 
oxygenation. 

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00:09:37,900 --> 00:09:41,300
One of the great oxidation event
which is approximately two point

158
00:09:41,300 --> 00:09:44,900
1 billion years ago and then 
another one, perhaps close to 

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00:09:44,900 --> 00:09:47,800
the Precambrian Cambrian 
boundary and that was the 

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00:09:47,808 --> 00:09:50,300
trigger perhaps for the Cambrian
explosion. 

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00:09:51,100 --> 00:09:56,500
But now, we don't see a 
narrative of a single increase 

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00:09:56,500 --> 00:09:58,900
episodic increase. 
We see these pulses of 

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00:09:58,900 --> 00:10:02,300
oxygenation coming and going. 
And these May well, Of started, 

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00:10:02,500 --> 00:10:06,400
in the EG car and possibly even 
older these pulses of 

165
00:10:06,400 --> 00:10:10,800
oxygenation where the shallow 
sea floor became oxygenated but 

166
00:10:10,800 --> 00:10:14,200
then and knocks it Waters 
impinged again on the shallow 

167
00:10:14,200 --> 00:10:17,300
shelves. 
So in other words it wasn't a 

168
00:10:17,300 --> 00:10:21,100
stepwise incremental increase. 
We just have these episodes of 

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00:10:21,100 --> 00:10:25,300
oxygenation coming and going but
with periods of more dominant 

170
00:10:25,400 --> 00:10:30,300
and oxy ER in between the other 
theme that's really emerging is 

171
00:10:30,300 --> 00:10:34,400
that are A shallow Marine 
shelves and possibly the Deep 

172
00:10:34,400 --> 00:10:39,200
Waters as well were incredibly 
heterogenous at the same period 

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00:10:39,200 --> 00:10:41,900
of time. 
We can go to Anna media. 

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00:10:41,900 --> 00:10:45,400
For example and say well I 
shallow shall cease were 

175
00:10:45,500 --> 00:10:48,200
oxygenated at this time but 
going through exactly that same 

176
00:10:48,200 --> 00:10:52,200
interval elsewhere. 
So for example China in fact 

177
00:10:52,200 --> 00:10:54,900
they were anoxic. 
So in other words we have this 

178
00:10:54,900 --> 00:10:59,000
very very heterogeneous 
distribution of dissolved oxygen

179
00:10:59,200 --> 00:11:03,800
in our seawater that time And 
this in fact, may be the key to 

180
00:11:03,800 --> 00:11:08,600
why the fossil records of these 
places are very, very different.

181
00:11:09,300 --> 00:11:12,400
I'm curious how it is. 
You can reconstruct what the 

182
00:11:12,400 --> 00:11:15,400
oxygen level was in the 
ediacaran. 

183
00:11:15,900 --> 00:11:18,800
Yes, there are various 
geochemical processes and they 

184
00:11:18,800 --> 00:11:21,700
fool. 
Very simply into two categories.

185
00:11:21,700 --> 00:11:26,100
One set, which are recording a 
global of station level. 

186
00:11:26,400 --> 00:11:29,400
So, these would be things like, 
uranium, Isotopes. 

187
00:11:29,900 --> 00:11:32,900
So we can interrogate it uranium
Isotopes, particularly in 

188
00:11:32,900 --> 00:11:37,100
limestone's and dolomites, and 
these can be used to. 

189
00:11:37,108 --> 00:11:42,800
Then reconstruct the degree of 
the seafloor globally that was 

190
00:11:42,800 --> 00:11:48,100
covered with and toxic Waters. 
They're rather tricky because 

191
00:11:48,200 --> 00:11:51,500
you have to make all sorts of 
assumptions about the Earth 

192
00:11:51,500 --> 00:11:53,700
State and they also need 
modeling. 

193
00:11:54,200 --> 00:11:58,500
So those are our Global proxies 
but potentially more powerful 

194
00:11:58,600 --> 00:12:02,400
are the use of local processes. 
You can actually look at the 

195
00:12:02,400 --> 00:12:07,300
condition just in a very small 
area, maybe a basin, or even one

196
00:12:07,300 --> 00:12:12,100
part of a sedimentary Basin and 
one of the key proxies used here

197
00:12:12,100 --> 00:12:15,200
is called iron speciation. 
It's a very simple, aqueous 

198
00:12:15,200 --> 00:12:19,600
geochemical technique where you 
extract all the iron from a 

199
00:12:19,600 --> 00:12:21,300
rock. 
But you divide that iron into 

200
00:12:21,300 --> 00:12:25,300
different types of iron and 
broadly into the amount of 

201
00:12:25,500 --> 00:12:28,100
highly reactive ion and the 
total amount of iron and it's 

202
00:12:28,100 --> 00:12:32,800
this ratio then it allows you to
Infer that, that sediment, was 

203
00:12:32,800 --> 00:12:35,900
deposited in the presence or 
absence of oxygen. 

204
00:12:36,400 --> 00:12:40,100
So, this is a powerful technique
which we can use to interrogate 

205
00:12:40,100 --> 00:12:44,500
at a really fine scale within 
basins individual sections 

206
00:12:44,500 --> 00:12:47,600
within the basins. 
And then compare the local redox

207
00:12:47,600 --> 00:12:50,000
Dynamics through time of what 
area. 

208
00:12:50,000 --> 00:12:53,300
So for example, the Biblia, the 
another area for example, 

209
00:12:53,700 --> 00:12:58,000
Siberia or South China, it's the
oxygen. 

210
00:12:58,100 --> 00:13:02,500
The main driving factor in the 
environment you That affects the

211
00:13:02,500 --> 00:13:06,500
evolution of Life at this point.
I think it's likely to be one of

212
00:13:06,500 --> 00:13:09,400
the key drivers but it's also 
likely not to be the only key 

213
00:13:09,400 --> 00:13:11,700
driver. 
We have other effects. 

214
00:13:11,700 --> 00:13:14,900
We have Global temperature, 
changes, climatic changes. 

215
00:13:15,500 --> 00:13:18,500
And another idea that is really 
gaining a lot of traction now, 

216
00:13:18,500 --> 00:13:23,200
is the availability of nutrients
so phosphorus and nitrogen. 

217
00:13:23,200 --> 00:13:26,600
For example, these are key 
building blocks of life and we 

218
00:13:26,600 --> 00:13:29,800
also know that as well as having
a very heterogeneous and very, 

219
00:13:29,800 --> 00:13:32,900
very dynamic. 
Like Oxygen history in our 

220
00:13:32,900 --> 00:13:36,500
shallow Marine seized during 
this time, we also have very 

221
00:13:36,500 --> 00:13:41,800
very heterogeneous nutrient 
input into the Seas and we know 

222
00:13:41,900 --> 00:13:44,700
from the modern that areas where
there's a lot of nutrients, 

223
00:13:44,700 --> 00:13:48,300
particularly nutrients either 
coming off land or nutrients, 

224
00:13:48,300 --> 00:13:51,800
upwelling from cold Waters. 
So, for example, the benguela 

225
00:13:51,800 --> 00:13:57,000
current that hits the southern 
African Coast, this creates 

226
00:13:57,000 --> 00:14:01,900
enormous productivity of life. 
So we think that These things 

227
00:14:01,900 --> 00:14:06,600
couple together, climatic 
changes changes in oxygenation 

228
00:14:06,600 --> 00:14:09,100
and changes in the availability 
of nutrients. 

229
00:14:09,400 --> 00:14:13,000
These all play a role in 
determining the evolution of 

230
00:14:13,000 --> 00:14:16,600
these early complex ecosystems. 
So I'm wondering if it's 

231
00:14:16,600 --> 00:14:20,400
possible to tease apart. 
These environmental factors that

232
00:14:20,400 --> 00:14:22,900
you talk about such as oxygen 
and the availability of 

233
00:14:22,900 --> 00:14:26,900
nutrients from internal 
biological factors that may have

234
00:14:26,900 --> 00:14:30,300
been at play here in the 
emergence and subsequent 

235
00:14:30,300 --> 00:14:32,300
flourishing of Life. 
Yes. 

236
00:14:32,300 --> 00:14:35,500
These so-called intrinsic 
characteristics are very, very 

237
00:14:35,500 --> 00:14:39,500
important and they should be 
seen in parallel with these 

238
00:14:39,500 --> 00:14:42,500
attempts, to interrogate the 
physical chemical World, which 

239
00:14:42,500 --> 00:14:46,300
we can from geochemistry and 
sedimentology and so forth. 

240
00:14:46,800 --> 00:14:49,800
And there's very, very 
interesting work taking place on

241
00:14:49,800 --> 00:14:53,700
trying to understand the 
evolution of Gene regulatory. 

242
00:14:53,700 --> 00:14:59,100
Networks conserved versus non 
conserve parts of the genome and

243
00:14:59,200 --> 00:15:03,900
trying to put these A genetics 
into the context of evolution. 

244
00:15:04,100 --> 00:15:06,900
So yes, this is a very, very 
important part of trying to 

245
00:15:06,900 --> 00:15:09,000
understand the emergence of 
complex life. 

246
00:15:09,700 --> 00:15:13,400
Can we use some of these 
intrinsic considerations to 

247
00:15:13,700 --> 00:15:18,100
understand what led to the 
emergence of biomineralization 

248
00:15:18,100 --> 00:15:21,500
or hard body parts that are 
shells and skeletons? 

249
00:15:22,500 --> 00:15:25,000
Yes. 
So one of the key incredible 

250
00:15:25,000 --> 00:15:29,200
Innovations in the history of 
complex life is this rise of 

251
00:15:29,200 --> 00:15:31,300
skeleton. 
So the ability of life If to 

252
00:15:31,300 --> 00:15:34,500
produce to co-opt minerals that 
are already there in the 

253
00:15:34,500 --> 00:15:38,600
environment and create a 
skeleton, or a shell out of 

254
00:15:38,600 --> 00:15:42,700
those minerals, one really 
interesting thing that's 

255
00:15:42,700 --> 00:15:47,500
emerging now is when you look at
the biological Affinity of these

256
00:15:47,500 --> 00:15:50,600
earliest by mineralize has, 
which appeared in the ediacaran 

257
00:15:50,600 --> 00:15:54,100
about 550 million years ago. 
I should say these earliest 

258
00:15:54,100 --> 00:15:56,200
purported Animal by mineralize 
errs. 

259
00:15:56,700 --> 00:15:59,100
These were the beginning of this
sort of root of the Cambrian 

260
00:15:59,100 --> 00:16:01,700
explosion. 
And then the number of Tim's 

261
00:16:01,700 --> 00:16:05,100
diversify the credibly in the 
Caribbean, both, in terms of the

262
00:16:05,100 --> 00:16:09,400
mineralogy, is our co-opted the 
types of skeletons and its sheer

263
00:16:09,400 --> 00:16:13,300
complexity of these skeletons. 
But one idea, is that these 

264
00:16:13,300 --> 00:16:18,400
skeletons appear independently 
in unrelated lineages and this 

265
00:16:18,400 --> 00:16:21,100
tells us that the biogeochemical
Machinery. 

266
00:16:21,100 --> 00:16:25,300
If you like all the genetic 
Machinery used to create by 

267
00:16:25,300 --> 00:16:30,000
minerals is a conserved feature,
long predating, the history of 

268
00:16:30,000 --> 00:16:33,300
metazoa Animals indeed. 
It may be common to all 

269
00:16:33,300 --> 00:16:37,000
eukaryotes and one of the 
prevalent ideas is that there 

270
00:16:37,000 --> 00:16:40,000
was this pre-existing Machinery?
That was simply co-opted for 

271
00:16:40,000 --> 00:16:43,500
another function, co-opted for 
the function of producing 

272
00:16:43,500 --> 00:16:46,900
skeletons. 
So this is led to the idea that 

273
00:16:47,200 --> 00:16:53,100
something must have happened. 
Perhaps in the environment, and 

274
00:16:53,100 --> 00:16:57,100
one aspect of that, is that the 
selection to have a skeleton. 

275
00:16:57,100 --> 00:16:59,500
May have simply changed. 
In other words, the fitness 

276
00:16:59,500 --> 00:17:03,300
gained from having a skeleton. 
Might have increased coincident 

277
00:17:03,300 --> 00:17:04,900
with the appearance of all these
skeletons. 

278
00:17:04,900 --> 00:17:08,700
And the key idea there is that 
we can invoke a rise in 

279
00:17:08,700 --> 00:17:12,200
predation pressure and the 
rising predation pressure. 

280
00:17:12,700 --> 00:17:16,200
Then gave added Fitness to 
animals. 

281
00:17:16,200 --> 00:17:19,800
That bore a protective skeleton.
And maybe this is the trigger 

282
00:17:19,900 --> 00:17:23,599
for why all these independent 
groups appear to produce 

283
00:17:23,700 --> 00:17:26,500
skeletons independently. 
But broadly around the same 

284
00:17:26,500 --> 00:17:30,100
time, when we spoke earlier you 
mentioned the idea that the rise

285
00:17:30,100 --> 00:17:32,700
in oxygen. 
Able to the Bayou to have a 

286
00:17:32,700 --> 00:17:36,800
higher metabolism, more energy, 
enabled them to move and 

287
00:17:36,800 --> 00:17:39,100
therefore to predate. 
And so the ability for one 

288
00:17:39,100 --> 00:17:41,500
animal to eat it, another was 
originally triggered by the 

289
00:17:41,500 --> 00:17:45,400
environment and then led to this
evolutionary change. 

290
00:17:46,000 --> 00:17:49,300
When now, as you say trying to 
tease apart, these intrinsic 

291
00:17:49,300 --> 00:17:52,100
biological features with these 
extrinsic triggers. 

292
00:17:52,500 --> 00:17:55,200
So, this is this idea that is 
really prevalent and 

293
00:17:55,200 --> 00:17:58,700
evolutionary studies of the 
relationship between 

294
00:17:59,100 --> 00:18:03,000
environmental change. 
And in creating environmental 

295
00:18:03,000 --> 00:18:06,000
opportunity and how life 
responds to that in other words 

296
00:18:06,000 --> 00:18:10,000
in evil, usually Innovation. 
And this is a really constant 

297
00:18:10,000 --> 00:18:13,200
dialogue and it's very, very 
difficult to tease them apart 

298
00:18:13,500 --> 00:18:16,200
because they often go 
hand-in-hand and there are 

299
00:18:16,200 --> 00:18:19,500
multiple feedbacks. 
I mean, one of the remarkable 

300
00:18:19,500 --> 00:18:23,000
things about our Earth, the most
remarkable thing about it is, as

301
00:18:23,000 --> 00:18:25,800
far as we know, it is the only 
place in the universe that 

302
00:18:25,800 --> 00:18:30,300
Harbours complex life. 
In fact, any life at all, But 

303
00:18:30,300 --> 00:18:34,600
this life co-evolved with the 
planet and all the things that 

304
00:18:34,600 --> 00:18:38,800
go to support this life are 
intrinsic to the workings of our

305
00:18:38,800 --> 00:18:41,200
planet. 
The carbon cycle, the sulfur 

306
00:18:41,200 --> 00:18:45,300
cycle, the nitrogen cycle, the 
regulation of climate, and so 

307
00:18:45,300 --> 00:18:48,900
forth. 
So teasing apart, chicken and 

308
00:18:48,900 --> 00:18:50,700
egg. 
In other words, what came first 

309
00:18:50,700 --> 00:18:53,700
did the environment create a 
permissive environment that 

310
00:18:53,700 --> 00:18:58,000
allowed life to respond, or did 
life, innovate, and in. 

311
00:18:58,000 --> 00:19:04,200
So doing Change the way, our 
biogeochemical cycles, operate, 

312
00:19:04,300 --> 00:19:07,900
and in so doing, create this 
extraordinary feedback on the 

313
00:19:07,908 --> 00:19:10,400
planet? 
This is getting to the heart of 

314
00:19:10,400 --> 00:19:13,700
what we're really interested in.
And of course, this is the Hub 

315
00:19:13,700 --> 00:19:18,000
of many, many research programs.
So does this mean that this 

316
00:19:18,000 --> 00:19:21,200
period of innovation, which 
perhaps originally, we thought 

317
00:19:21,200 --> 00:19:25,600
was in the Cambrian can be 
pushed back, largely to the late

318
00:19:25,800 --> 00:19:30,000
Precambrian, and that we see 
evolutionary ancestors of Of 

319
00:19:30,300 --> 00:19:33,700
Cambrian life forms in the 
ediacaran? 

320
00:19:34,700 --> 00:19:38,100
Well, I'm certainly one of those
that is convinced that we can 

321
00:19:38,100 --> 00:19:41,700
see the roots of these 
Innovations in the ediacaran. 

322
00:19:42,100 --> 00:19:44,500
Of course, we should always 
remember that the fossil record 

323
00:19:44,500 --> 00:19:48,700
that we have is only the very 
incomplete record. 

324
00:19:49,100 --> 00:19:52,300
And these fossils are certainly 
only recording the minimum age 

325
00:19:52,400 --> 00:19:56,300
of any of these groups and what 
is the origin of these groups? 

326
00:19:56,300 --> 00:20:00,400
And if we look at a molecular 
phylogeny is for example, The 

327
00:20:00,400 --> 00:20:05,200
Proposal is that many of these 
groups have really old Origins. 

328
00:20:05,200 --> 00:20:08,600
So for example, molecular 
phylogeny is suggest that the 

329
00:20:08,600 --> 00:20:13,200
origin of the animals themselves
could be anywhere between eight 

330
00:20:13,200 --> 00:20:16,100
hundred million years ago to 600
million years ago. 

331
00:20:16,900 --> 00:20:20,300
We have no record of animal 
fossils then at all. 

332
00:20:20,400 --> 00:20:22,300
But this is what the phylogeny 
is tell us. 

333
00:20:23,400 --> 00:20:25,700
So, it should come as no 
surprise that we can 

334
00:20:25,700 --> 00:20:29,700
increasingly make some links 
between EJ car and animals. 

335
00:20:29,900 --> 00:20:33,900
And Cambrian animals. 
One example could be this 

336
00:20:33,900 --> 00:20:37,400
ediacaran animal called Nama 
Colossus, it's known from 

337
00:20:37,400 --> 00:20:41,900
Namibia Canada, South America, 
and security. 

338
00:20:41,900 --> 00:20:46,000
It'll goblet shape fossil it has
a goblet shape skeleton, but 

339
00:20:46,000 --> 00:20:48,900
we've recently found some 
exceptionally preserved 

340
00:20:48,900 --> 00:20:52,300
individuals that have soft 
tissue and there's soft tissue. 

341
00:20:52,300 --> 00:20:54,000
Of course. 
It depends on how you interpret 

342
00:20:54,000 --> 00:20:56,200
the soft tissue. 
But there is a curious structure

343
00:20:56,200 --> 00:20:59,700
inside this skeleton. 
That is preserved. 

344
00:20:59,900 --> 00:21:02,900
Preserved in Paris and it's a 
tube of pyrite. 

345
00:21:03,800 --> 00:21:07,100
And we believe the best 
explanation for this tubular 

346
00:21:07,100 --> 00:21:10,900
structure, which is a symmetric 
and slightly j-shaped, is that 

347
00:21:10,900 --> 00:21:15,500
it's a gut and we think it's a 
gut of a group known as the 

348
00:21:15,500 --> 00:21:16,600
loafer truckers. 
Oh, ER. 

349
00:21:16,700 --> 00:21:21,400
So this is a group that today 
represents about a third of all 

350
00:21:21,600 --> 00:21:26,300
Marine, invertebrates related to
the mollusks, the clams, the 

351
00:21:26,300 --> 00:21:29,700
bracket pods, the bryozoa, which
little tiny Colonial animals. 

352
00:21:29,800 --> 00:21:32,500
Mi. 
So we think here we have a link 

353
00:21:32,500 --> 00:21:36,100
between these Cambrian and the 
terminal edia Karim. 

354
00:21:36,700 --> 00:21:38,900
That's interesting. 
So from what you've said, it 

355
00:21:38,900 --> 00:21:42,500
sounds like there was more 
continuity between the ediacaran

356
00:21:42,500 --> 00:21:45,400
and the Cambrian than we first 
thought and was there. 

357
00:21:45,400 --> 00:21:49,000
In fact, a mass extinction or 
some kind of dramatic 

358
00:21:49,000 --> 00:21:52,400
environmental event that 
actually did take place at the 

359
00:21:52,400 --> 00:21:55,900
ediacaran Cambrian boundary. 
Well, the nature of this 

360
00:21:55,900 --> 00:21:58,400
boundary is really hotly 
debated. 

361
00:21:59,200 --> 00:22:01,600
What are the issues? 
Was, is that many of these 

362
00:22:01,600 --> 00:22:04,600
boundaries, accessions, globally
are incomplete. 

363
00:22:04,900 --> 00:22:08,800
Many of them that have the 
richest fossils don't have these

364
00:22:08,800 --> 00:22:11,800
key, Ash beds to date. 
So this is a real problem for 

365
00:22:11,800 --> 00:22:15,700
dating the order of events and 
also correlating globally 

366
00:22:15,700 --> 00:22:19,000
between sections of a remote 
from each other. 

367
00:22:19,700 --> 00:22:21,800
So there's two schools of 
thought one is that yes, there 

368
00:22:21,800 --> 00:22:25,000
was an Extinction. 
We see it this time at 

369
00:22:25,000 --> 00:22:29,000
incredible - isotope Excursion 
in carbon which suggests there 

370
00:22:29,000 --> 00:22:32,100
was a profound. 
Found perturbation of the carbon

371
00:22:32,100 --> 00:22:34,700
cycle. 
And some have suggested that 

372
00:22:34,700 --> 00:22:39,200
this coincides with large 
igneous Province magmatic 

373
00:22:39,200 --> 00:22:41,900
activity. 
So this is very similar to the 

374
00:22:41,900 --> 00:22:44,700
mass extinction events that we 
see later in the phanerozoic. 

375
00:22:45,000 --> 00:22:48,800
Many of them, but not all can be
associated with these large 

376
00:22:48,800 --> 00:22:51,400
igneous provinces. 
These are provinces where you 

377
00:22:51,400 --> 00:22:55,900
have a huge amount of 
Continental magmatic production 

378
00:22:55,900 --> 00:22:59,100
over a very long period of time,
millions of years and these 

379
00:22:59,100 --> 00:23:03,700
create Rapid and sustained 
global warming and offered this 

380
00:23:03,700 --> 00:23:06,700
global warming can lead to the 
ocean circulation, becoming 

381
00:23:06,700 --> 00:23:11,400
sluggish and noxious developing 
one school of thought, suggest 

382
00:23:11,400 --> 00:23:14,400
that we had an event like this, 
a mass extinction event. 

383
00:23:14,700 --> 00:23:19,100
So perhaps anoxia triggered by 
this volcanism that created an 

384
00:23:19,100 --> 00:23:23,400
extinction of the so-called 
ediacaran biota and in effect. 

385
00:23:23,400 --> 00:23:26,400
Paved the way for the 
flourishing, beginning of the 

386
00:23:26,400 --> 00:23:30,300
Cambrian, biota the other school
of thought, It is that there 

387
00:23:30,300 --> 00:23:34,200
wasn't a mass extinction, there 
may have been perhaps a more 

388
00:23:34,200 --> 00:23:39,400
modest turnover and nonetheless,
we can determine transitional 

389
00:23:39,400 --> 00:23:44,100
biota across this interval. 
Indeed, we can find skeletal 

390
00:23:44,100 --> 00:23:48,100
fossils, which were previously 
thought to be entirely lower 

391
00:23:48,100 --> 00:23:50,200
camera. 
We can now find them in Egypt. 

392
00:23:50,200 --> 00:23:54,800
Karan sediments, they are 
transitional what we call small 

393
00:23:54,800 --> 00:23:58,900
Shelly fossils. 
So, I slightly fall into the 

394
00:23:58,900 --> 00:24:02,900
second category. 
And I believe that there wasn't 

395
00:24:02,900 --> 00:24:05,800
a mass extinction, I may be 
proved wrong, but I think at the

396
00:24:05,800 --> 00:24:09,600
moment, the evidence for mass 
extinction is not compelling but

397
00:24:09,600 --> 00:24:13,900
rather we see a series of 
transitional by auteurs. 

398
00:24:14,300 --> 00:24:17,300
So in other words we see this 
slight turn over at the boundary

399
00:24:17,700 --> 00:24:20,900
but we see many turnovers before
that and we see turnovers 

400
00:24:20,900 --> 00:24:25,200
afterwards as well so it may be 
possible to reframe The 

401
00:24:25,200 --> 00:24:30,100
Narrative of the Cambrian 
explosion as perhaps Not being 

402
00:24:30,100 --> 00:24:35,000
Cambrian at all and simply being
one of the several radiations of

403
00:24:35,000 --> 00:24:37,700
complex. 
Life animal life, indeed. 

404
00:24:38,200 --> 00:24:40,500
That actually precedes the 
Cambrian explosion and the 

405
00:24:40,500 --> 00:24:44,700
Cambrian explosion is one of the
final manifestations of this 

406
00:24:44,700 --> 00:24:48,300
event. 
However, having said that, what 

407
00:24:48,300 --> 00:24:51,900
seems to be very characteristic 
of the Cambrian explosion is 

408
00:24:51,900 --> 00:24:55,500
this genuine explosion of 
fossils of predators with? 

409
00:24:55,500 --> 00:24:59,100
I think that is a distinctive 
part of the Cambrian but the 

410
00:24:59,100 --> 00:25:02,100
Caribbean exposure Couldn't have
happened without all these other

411
00:25:02,400 --> 00:25:05,300
radiation of all these other 
transitional by auteurs before 

412
00:25:05,300 --> 00:25:08,700
that. 
So, does that suggest the view 

413
00:25:08,700 --> 00:25:11,900
that the Cambrian explosion, 
when it actually did take place 

414
00:25:11,900 --> 00:25:16,700
was more of a intrinsic 
biologically driven change. 

415
00:25:17,100 --> 00:25:19,800
Yes, it is a very interesting 
and fundamental question, 

416
00:25:19,800 --> 00:25:23,600
there's no doubt that ecological
drivers were very important in 

417
00:25:23,600 --> 00:25:27,200
the Cambrian explosion. 
We know how powerful a driver is

418
00:25:27,200 --> 00:25:30,500
of the rise of predators and we 
have this this phenomenon known 

419
00:25:30,500 --> 00:25:33,400
as an arms race. 
It's really form of evolutionary

420
00:25:33,400 --> 00:25:35,700
escalation. 
In other words, a new Predator 

421
00:25:35,700 --> 00:25:39,900
revolves with new horrible 
mouth, parts, or grasping 

422
00:25:39,900 --> 00:25:43,200
appendages. 
And so the prey has to respond 

423
00:25:43,200 --> 00:25:47,300
by in some way acquiring some 
sort of either defensive 

424
00:25:47,300 --> 00:25:50,400
skeleton or change. 
Its Behavior, becoming 

425
00:25:50,400 --> 00:25:55,000
nocturnal, for example, or 
hiding in a crevice, this ends 

426
00:25:55,000 --> 00:25:57,700
up in this arms, race is a 
constant arms race. 

427
00:25:58,200 --> 00:26:02,000
So this is certainly important. 
But we also know that the lower 

428
00:26:02,000 --> 00:26:06,400
can be was still a time of very 
Dynamic Redux, can you explain 

429
00:26:06,400 --> 00:26:10,200
what you mean by redox? 
So by redox, I simply mean the 

430
00:26:10,200 --> 00:26:13,500
distribution of oxygen and I 
normally mean the distribution 

431
00:26:13,500 --> 00:26:17,800
of dissolved oxygen seawater. 
So in other words where we had 

432
00:26:17,800 --> 00:26:21,100
free oxygen, we can refer to 
that as a toxic conditions, 

433
00:26:21,100 --> 00:26:22,800
where there was no oxygen at 
all. 

434
00:26:23,000 --> 00:26:27,700
We can refer to that as anoxic 
conditions and all sorts of 

435
00:26:27,700 --> 00:26:31,900
other shifts in the carbon side.
Other Cycles were ongoing at 

436
00:26:31,900 --> 00:26:34,900
this time. 
So I think again, we can't just 

437
00:26:34,900 --> 00:26:37,900
pin all this on one factor, all 
these factors are 

438
00:26:37,900 --> 00:26:40,900
interconnected, and I think this
is what makes the ediacaran. 

439
00:26:40,900 --> 00:26:45,800
So phenomenally interesting is 
that we have to unpick all these

440
00:26:45,800 --> 00:26:48,700
factors and really understand 
how they are interconnected and 

441
00:26:48,700 --> 00:26:51,600
understand the drivers and the 
feedbacks. 

442
00:26:52,400 --> 00:26:56,700
It's many, many lifetimes work. 
I'm struck by the fact that, 

443
00:26:57,300 --> 00:27:01,000
although, we've now pushed back 
the origin of complex life into 

444
00:27:01,000 --> 00:27:04,700
the ediacaran, a few tens of 
millions of years into the 

445
00:27:04,700 --> 00:27:08,700
Precambrian. 
That's not much in the grand 

446
00:27:08,700 --> 00:27:12,700
scheme of things. 
It still leaves well, over three

447
00:27:12,700 --> 00:27:15,800
billion years of History, 
without complex life. 

448
00:27:16,600 --> 00:27:19,900
Can you speculate why? 
It took so long to arrive. 

449
00:27:20,800 --> 00:27:23,700
So, why it took so long for 
complex life to appear is 

450
00:27:23,700 --> 00:27:28,500
unresolved, and it is a 
tremendous source of current 

451
00:27:28,500 --> 00:27:31,900
research. 
One that pervasive ideas, we 

452
00:27:31,900 --> 00:27:34,600
have this phenomenon called the 
boring billion which is a 

453
00:27:34,608 --> 00:27:37,200
billion years when not much 
seemed to have happened or at 

454
00:27:37,200 --> 00:27:39,000
least, we thought not much 
happened. 

455
00:27:39,400 --> 00:27:42,700
So in other words Eeveelution, 
it just seemed to be the same 

456
00:27:42,700 --> 00:27:44,300
fossils from beginning to the 
end. 

457
00:27:44,800 --> 00:27:48,200
However, this record is really 
starting to be interrogating, a 

458
00:27:48,200 --> 00:27:52,700
lot more detail now and without 
doubt we will be revealing 

459
00:27:53,000 --> 00:27:56,900
exciting, new fossil finds. 
But also the geochemistry of 

460
00:27:56,900 --> 00:27:59,500
this interval is being 
interrogated and it's not boring

461
00:27:59,500 --> 00:28:02,200
at all. 
The seem to be episodes of 

462
00:28:02,200 --> 00:28:05,000
oxygenation. 
In other words, this pattern 

463
00:28:05,000 --> 00:28:08,700
that we see in the other car and
of these pulses of oxygenation, 

464
00:28:08,800 --> 00:28:12,700
maybe hand-in-hand with pulses 
of nutrients, that may well be a

465
00:28:12,700 --> 00:28:16,400
motif that we can trace back 
into this boring billion. 

466
00:28:17,000 --> 00:28:22,400
So we're constantly pushing back
the origin of these key building

467
00:28:22,400 --> 00:28:24,500
blocks. 
If you like further back into 

468
00:28:24,500 --> 00:28:25,900
time. 
And I think that this boring 

469
00:28:25,900 --> 00:28:30,200
billing will prove anything but 
boring in the years to come So 

470
00:28:30,200 --> 00:28:34,200
if you were to speculate about 
EXO life or life on any other 

471
00:28:34,200 --> 00:28:38,000
planet, would you expect 
therefore that there are some 

472
00:28:38,200 --> 00:28:42,500
fundamental constants of nature?
If you like that it really does 

473
00:28:42,500 --> 00:28:46,100
take billions of years for the 
appropriate complexity to 

474
00:28:46,100 --> 00:28:48,300
evolve. 
Whether it's what can be 

475
00:28:48,300 --> 00:28:51,800
permitted by the environmental 
factors or whether what is 

476
00:28:51,800 --> 00:28:55,200
needed in the molecular biology 
to biomass sufficient 

477
00:28:55,200 --> 00:28:58,600
complexity. 
Yes, this is a prevalent theme 

478
00:28:58,600 --> 00:29:04,300
that simply Life needs a very, 
very long time to assemble the 

479
00:29:04,300 --> 00:29:08,600
necessary genetic Machinery, the
gene regulatory Frameworks and 

480
00:29:08,600 --> 00:29:11,400
so on. 
But of course, we only have one 

481
00:29:11,400 --> 00:29:16,700
example Earth, we cannot be run 
the experiment, and, of course, 

482
00:29:16,700 --> 00:29:21,000
we know that it's very, very 
difficult to Define life, Define

483
00:29:21,000 --> 00:29:24,700
this quality, this elusive 
quality that we call life and 

484
00:29:24,700 --> 00:29:27,600
there are some wonderful 
definitions out there in terms 

485
00:29:27,600 --> 00:29:29,900
of self-regulation and 
homeostasis. 

486
00:29:30,000 --> 00:29:34,600
Yes, but we're in the midst of a
pandemic, which is caused by a 

487
00:29:34,608 --> 00:29:38,600
virus. 
And many would argue a virus 

488
00:29:38,600 --> 00:29:42,500
isn't living, but look at the 
power of a virus. 

489
00:29:42,600 --> 00:29:46,000
Look at the power of something 
that is not living, but it has 

490
00:29:46,000 --> 00:29:50,500
this extraordinary ability to 
replicate by co-opting, human 

491
00:29:50,500 --> 00:29:54,900
genetic machinery and get better
at it tremendously. 

492
00:29:54,900 --> 00:29:59,500
So it comes down to. 
I suppose our ideas about what 

493
00:29:59,500 --> 00:30:01,300
is life. 
What is complexity? 

494
00:30:01,600 --> 00:30:06,500
We place animals at the top of 
the tree of life, Because we're 

495
00:30:06,500 --> 00:30:12,800
one and we're big and we appear 
to be in control, but maybe we 

496
00:30:12,800 --> 00:30:15,700
should rethink the way we 
perceive the Tree of Life. 

497
00:30:17,000 --> 00:30:19,000
Rachel would thank you very 
much. 

498
00:30:19,500 --> 00:30:22,200
Thank you very much Oliver. 
It's been a pleasure for more 

499
00:30:22,200 --> 00:30:25,400
about geology, b, as well as 
pictures and diagrams that 

500
00:30:25,400 --> 00:30:27,800
illustrate. 
This podcast, you can go to 

501
00:30:27,800 --> 00:30:29,500
geology B.com