The (Reverse) History of Evolution

Wait But Why offers a crudely-drawn-yet-still-awesome history of evolution, taking us back through time:

I don’t know what to tell you. This is a part of your lineage.

I want you to pause and just ponder for a second that I’m not inventing silly shit here — if you take your father, and your father’s father, and do that 435,000,000 times, you’ll end up at a jellyfish. Evolution is boggling.

One of the takeaways is still awe-inspiring every time I hear it (emphasis theirs):

How incredibly unlikely it is that you exist. Going back to the first particle of life, there are over a trillion fathers and father’s fathers that eventually ended with your parents conceiving you. And if any one of those fathers (or mothers) had died before reproducing — if any of the millions of fish in your line had been prematurely eaten, if any of the millions of rodents in your line had been crushed by a falling tree as a baby — you would not exist. Maybe someone similar to you — but not you.

If you spot any mistakes in the explanations, let them know!

David McNerney

…and father’s father’s fathers and father’s father’s father’s fathers and father’s father’s father’s father’s fathers….

Sorry, couldn’t resist, and it’s strangely seasonal.
Rhodent

Wanna know what’s a surprisingly easy way to blow people’s minds? Point at a nearby tree, and mention the fact that if you go far enough back, that tree and the person you’re speaking to are cousins. I once sat down and did the math, and came up with the result that saying the tree is your one-billionth cousin is a reasonable estimate (i.e., give or take a thousand generations). It makes perfect sense if you stop to think about it, but most people never do.
Intelligent Donkey

Thou shalt not think, for that maketh baby Jesus cry.
Vijen

Fun, but Richard Dawkins has done it more eloquently in “Ancestor’s Tale”.
Goldstein’s Nephew

If there are only a very few mutations that end up being beneficial, I would like to see the math that shows that there have been enough of those kind of mutations to account for the transition from simple cells to the human brain in 435 m genertions.

Not denying it at this point, just asking for an approximate number of how many mutations…that ended up being benefical…that would take.
Goldstein’s Nephew

Hmmmm…you did the math?

Can you show your work?
Justatron

Ancestor’s Tale remains my favorite Dawkins book thus far, but this is still a great little summary…I need to share it with my biology students…
Justatron

Sean Carroll’s book, “The Making of the Fittest” does a good job of dealing with the mathematical probabilities of mutations leading to fundamental changes in organisms…
Lurker111

I’ve often wondered what Nth cousin X times removed I and my Big Orange Kitty are.
DavidMHart

Wait – is that actually true? I don’t have time to go digging right now, but I thought that cnidarians and vertebrates were two branches of animal that both diverged from simpler animals, so that, whatever the common ancestor of you an a jellyfish might have been, it didn’t bear any resemblance to a jellyfish.

Also, I have to slightly query the list of ‘fathers’ – male and female only make sense once you get to sexually reproducing species that are non-hermaphroditic. Before that point, to the extent you could sex such animals at all, it would make more sense to call them asexually reproducing mothers, would it not?
WalterWhite007

How cumms all theez begats idun’t in da holey bible ifin theyiz tru??
..
you cant explane that!!
Art_Vandelay

Richard Dawkins does this in the iPad version of Magic of Reality.
Anat

Dawkins’ book is properly referenced in the post.
Jon Binkley

I don’t think pushing incorrect “facts” about evolution helps anyone. We did not evolve from jellyfish — we and jellyfish evolved from a common ancestor (that looked like neither jellyfish nor us). We did not evolve from rodents — we and rodents evolved from a common ancestor.

It’s like saying we descended from our sibling or cousin. We did not. We and our siblings descended from common parents; we and our cousins descended from common grandparents.

Think TREE, not LADDER.
Speedwell

Calculating the probability that I exist is reasonably straightforward given the fact that, you know, I actually exist. (waves)
GubbaBumpkin

I don’t have time to go digging right now, but I thought that cnidarians
and vertebrates were two branches of animal that both diverged from
simpler animals, so that, whatever the common ancestor of you an a
jellyfish might have been, it didn’t bear any resemblance to a
jellyfish.

That’s right.

You can find recent articles about comb jellyfish being the first branch off the animal lineage leading to humans. But:

1) Comb jellyfish are not the same as the common “jellyfish.”
2) The common ancestor should not be confused with a current species, which has been evolving from the common ancestor precisely as long as you have been.
GubbaBumpkin

if any of the millions of fish in your line had been prematurely eaten,
if any of the millions of rodents in your line had been crushed by a
falling tree as a baby — you would not exist.

Fish – yes. Some of our ancestors would qualify as “fish.” But these were not the modern teleosts we think of first when the word “fish” appears.

Rodents – no. None of your ancestors were rodents. We are primates, not rodents.
GubbaBumpkin

TimeTree

How it Works:
Two species or higher taxa are queried (e.g., cat and dog).
TimeTree compares all taxa in one inclusive group (e.g.,
Feliformia) with those in the other group (e.g., Caniformia) to find all
published times of divergence for the evolutionary split.

Human and cat: 94.2 million years ago (plus or minus).

Human and jellyfish (Polyorchis penicillatus) 855.3 million years ago

Human and pine tree: 782.7 million years ago.
* Clearly this result does not fit in with the others. The algorithm averages various estimates.

Human and maple tree: 1369 million years ago.
GubbaBumpkin

Jellyfish (Polyorchis penicillatus) and comb jelly (e.g. Pleurobrachia): 940 million years ago

Human and pleurobrachia: 1147 million years ago

Human and jellyfish: 855.3 million years ago

The results above are clearly limited (i.e. wrong) in that two of those lineages should share a common ancestor with each other more recently than with the third, so the TimeTree distance for each with the third should be the same.

Looking back this far taxes the algorithm. For humans and jellyfish, for
example, it averages estimates from 604 to 1298 million years ago.
GubbaBumpkin

Human and Salmonella ( a type of bacteria): 2535 million years ago
GubbaBumpkin

Not denying it at this point…

You don’t have enough familiarity with the material that I value your opinion on the topic; so even if you did deny it, all I would have to offer you is pity.
GubbaBumpkin

Michael Behe being cross-examined by attourney Eric Rothschild in the Kitzmiller v. Dover trial, 2005

Q. Professor Behe, what I’ve showed you is Plaintiffs’ Exhibit 721. Do you recognize that as the article you wrote with David Snoke entitled Simulating Evolution by Gene Duplication of Protein Feature that Requires Multiple Amino Acid Residues?
A. Yes.

…

A. Let me just finish. Depending on — as we emphasize in the paper, it depends on the population size. And, of course, prokaryotes can oftentimes grow to very large population sizes.
Q. And here the conclusion, the calculations you concluded was that, if you had a population of 10 to the 9th power, that’s a population of 1 billion?
A. That’s correct.
Q. To produce a novel protein feature through the kind of multiple point mutations you’re talking about, it would take 10 to the 8th generations, that’s what it says in the abstract, correct?
A. If, in fact, it was — if, in fact, the intermediate states were not selectable.
…

Q. What I’ve marked as Exhibit P-756 is an article in the journal Science called Exploring Micro–
A. Microbial.
Q. Thank you — Diversity, A Vast Below by T.P. Curtis and W.T. Sloan?
A. Yes, that seems to be it.
Q. In that first paragraph, he says, There are more than 10 to the 16 prokaryotes in a ton of soil. Is that correct, in that first paragraph?
A. Yes, that’s right.
Q. In one ton of soil?
A. That’s correct.
Q. And we have a lot more than one ton of soil on Earth, correct?
A. Yes, we do.
…
rg57

“How incredibly unlikely it is that you exist”

What nonsense. I must exist. My parents had no other choice but to produce me. And theirs before them, etc. I will die when I must die.

You’re not deterministic?

OK then. There are 7 billion or so other humans on this planet, and they exist. Is there something so particularly unique about me that we should point me out, cast aside the other billions, and say “YOU, it is so unlikely that YOU exist”? That’s just narcissism.

And that’s only at this moment. What of the countless other planets, and other times?

It is perfectly ordinary that any of us exist.
rg57

I think you’re making the opposite mistake. Just because a classification exists today doesn’t mean that nothing in the past fits into it.

We still refer to ancient bacteria as bacteria, for example. And surely you’d agree that we came from animals, somewhere along the way. At what point does it break down: kingdom, class, family,…?

(Also, we’d be mistaken to overlook the fact that, yes, some people are descended from siblings or cousins)
GubbaBumpkin

While acknowledging your point, Jon Binkley did not make the mistake you suggest.

The picture above is of a modern jellyfish. The common ancestor of humans and jellyfish is so far in the past that describing the common ancestor would be very difficult.

Yes, we came from (and still are) animals. What does that have to do with the fact that we are not, and not descended from, rodents?

If you read books on the topic, you will find mesozoic mammals described as “shrew-like.” Shrews are not rodents.

We are primates. Primates probably descended from insectivores. But rodents are a different branch which our ancestors never climbed.
invivoMark

Jon is correct. Our ancestors include bacteria, fish, amphibians, reptiles, and small shrew-like mammals. Our ancestors do not include jellyfish, nor anything we would classify as a cnidarian. Nor do they include anything we would classify as a rodent.

Ancestry once you get to single-celled organisms gets a little fuzzy, since bacteria exist in an ocean of shifting and swapping genes. However, we did not directly descend from an organism that could photosynthesize.
invivoMark

That would be remarkable indeed!

But that isn’t even close to what happened. There hasn’t been such a thing as a “simple cell” in 3 billion years. Bacteria are incredibly complex! There are over a hundred thousand protein molecules in a single cell of E. coli at any given time.

Multicellular life has been around for over a billion years. At that point, cells were efficiently producing and storing large amounts of energy. They were living in large colonies, and had vast communication networks by which they could send signals from one end of the colony to the other. Cells within a colony were specializing, with only some of the cells focusing on reproduction, leaving the rest to focus their energy on other activities like foraging or swimming away from toxins.

The bigger these colonies became, the more complex their communication networks had to become. They had to send signals rapidly across larger distances, so they could react to rapid changes in their environment. After 500 million years, these cell colonies had become so efficient at sending signals that they could start growing to even bigger sizes and had organs specialized for movement, for information gathering, and for information processing. You had colonies of cells that could swim, that could see other colonies of cells and decide whether the other colony of cells was small enough to eat, or if they should swim away from the other colony of cells to avoid being eaten.

These swimming colonies of cells had brains. They had cells specialized for sending signals to and from the brain. These cells could specialize so effectively, not because they had so many more genes than their ancestors 500 million years prior, but because they had more complex regulation of a very similar set of genes. Gene regulation is a very simple thing to evolve. It only takes a few base pair changes to make a big difference. After millions of years, it ends up a bit of a kluge job, but it does what it needs to.

So now you have about 500 million generations to get to a human brain. Not from simple cells, but from incredibly complex colonies of highly specialized cells, with entire organs dedicated to sending and receiving information.

How many beneficial mutations would that take? Do you see how that question is a red herring? By the time you start counting, you’re working with a cluttered, complicated, kluged product of billions of years of evolution. You’re working with something with ten thousand genes all regulated in different and complex ways. There are a million ways to make a brain, and evolution works with what it has. You could make a human-like brain with just a few thousand well-placed mutations in a sea urchin genome, but evolution might take a different path than the one you chose.
Jon Binkley

I actually agree with your point that contemporary taxonomic classifications shouldn’t be imposed upon ancient taxa. When the group of animals that ultimately became jellies first split from the group of animals that ultimately became us, had we been there to observe it we would have called it “speciation”, not “phylumation”!

But the point is that the common ancestor was no more a jelly than it was a human, and is equally distant, evolutionarlily, from both.
baal

Maybe they are confused about the “tiny shrew like ancestor”?
baal

Probability of a existing thing to exist? 1!
Camorris

I find it simple amazing how many current vertebrate animals share the same skeletal layout of skull, spine with tail, and four limbs. This part of the gene has survived through many evolutions our ancestors.
CanuckAmuck

What a fun resource! Thanks!

(Yes, I’m nerdy enough to think of that sort of thing as fun.)
Alierias

My 8 year old and I discussed just that idea this morning. We share DNA from that ever so distant ancestor, when we were still bacteria.
Alierias

Read “Our inner fish” by Neil Shuban, or “At the Waters Edge” by Carl Zimmer for a good mass market explanation. Or “What Evolution Is” by the late great Ernst Mahr.
Evolution has been very thrifty with morphology because of the genetics of our ancestors, nothing amazing about it. There is very powerful selective forces coming to bear upon much of our genes, meaning that most mutations are negatively selected against. In other words, you don’t live to reproduce, so your mutation for no spine, aka spina bifida, is not passed on.
Vertebrates with extra limbs are born rarely, but they don’t seem to thrive or breed successfully. Perhaps having more than 4 limbs is too expensive metabolically to too offset any speed bonus, so therefore we haven’t seen any successful mutations leading in this direction. There’s always a reason.
closetatheist

I kind of hate to be “that person” but, why must it be our fathers lineage we look at? As I understand it the male gender is the result of a mutation anyway, so wouldn’t it be just as representative, or even better, to look through our mother’s mother’s mother’s……..lineage?
quasibaka

Just goes to show that all living beings are connected by a creative consciousness . The physical manifestation of quantum non-locality that exists .Now we just need to understand and tap into that inspirational unity to become enlightened .

[/quantum woo]
Gehennah

Also, if your parents had sex a different time, you likely wouldn’t be you either.
Gehennah

The very specific, unique set of DNA that makes up you, is extremely unlikely.

Just as any specific raindrop has extremely unlikely to hit the tip of my car antenna. It still happens all of the time, but any minor change and that drop won’t hit it, another will.
Little_Magpie

only thing is that of course it’s not so much a modern jellyfish as a precursor to us and jellyfish that might have looked more like the jellyfish than like us.
bismarket

I know it’s not true but i would kinda like it if my line & Bill O’Reiley’s split some time before Jellyfish, know what i mean?