Does neutral evolution explain the genetic differences between humans and chimpanzees

Conversation
#1

I watched the following video where Dr. Swamidass tries to explain the genetic differences between humans and chimpanzees using the concept of Distance = Rate x Time, neutral evolution.

(41min).

There is a flaw in this argument. What that flaw concern is the meaning of beneficial, neutral, and detrimental mutations. Those adjectives for the word mutation concern reproductive fitness. A beneficial mutation increases reproductive fitness, a neutral mutation does not change reproductive fitness, and a detrimental mutation reduces reproductive fitness.

At this time, there are about 7.1 billion humans on earth.

At this time, there are about 300,000 common chimpanzees on earth.

The chimpanzee population size is about 0.0042% of the size of the human population size. Therefore, humans have vastly greater reproductive fitness than chimpanzees. If you want to claim that humans and chimpanzees evolved from a common ancestor, humans must have gotten some beneficial mutations along the way to give that vastly greater reproductive fitness. How exactly are these adaptive mutations accumulated to give this vastly greater reproductive fitness that humans demonstrate over chimpanzees?

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Roles of Natural Selection and Cognition in Evolution and Population Size?
A problem with molecular evolution?
#2

What do you mean “if you want to claim”? How can you possibly ignore all the evidence that this is true? And of course humans have fixed some beneficial mutations. How many do you think there have been? Certainly it’s not any significant fraction of the approximately 20 million fixed changes in the human lineage, or would you disagree? If these beneficial mutations are relatively few, how can that affect @swamidass’s argument?

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#3

How many beneficial mutations does it take to get a more than four-order of magnitude increase in reproductive fitness (300,000 vs >7billion)? If you can, tell us how beneficial mutations accumulate on a lineage. If you have trouble with that math, you can find it here:
The Kishony Mega-Plate Experiment, a Markov Process

#4

Nice to see you again @kleinmar. I think you were last here two years ago (Kleinman: Four Questions About Evolution).

You are a legitimate scientist who has published in adjacent areas, though you do hold a minority position. Out of respect for you, and to keep this conversation on track, @moderators will limit this thread to qualified scientists prepared to engage with you with respect and substance.

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#5

At least one. Possibly several.

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#6

The huge increase in human population didn’t all come directly from beneficial mutations. There were a few beneficial mutations which increased our intelligence and thereby our tool making capability. This extra capability allows humans to be the first species to manipulate their environment on the scale we do, a manipulation which led to the explosion in population.

Fixed typo

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#7

You answer a question with a question? Also, you would appear to misunderstand even the concept of absolute fitness. Wouldn’t that be the per-generation increase rather than the total increase over millions of years?

Have you even submitted that anywhere?

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#8

Population size is not correlated with fitness. Instead, fitness is relative to environment and other members of the population. It is not, therefore, a fixed quantity.

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#9

Define fitness any way you want but clearly, humans have vastly out-replicated chimpanzees.

And yes, the paper is in peer-review at this time. If you read this paper, do you understand the problem with the Jukes-Cantor (and derivative) model(s) of DNA evolution?

#10

So, how many replications does it take for a beneficial mutation to occur, and how does a lineage accumulate a set of beneficial mutations?

#11

Kleinman refers to absolute fitness, not relative fitness, though he uses even that term incorrectly.

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#12

So, how many replications does it take for a beneficial mutation to occur?

#13

I appreciate that. And I don’t mind holding the minority view.

#14

Where?

I understand that you are sorely mistaken. If you have submitted it to a legitimate, on-topic journal, the reviewers will doubtless inform you.

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#15

At least one. Possibly several. Obviously.

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#16

Then, why do you assume you can calculate evolutionary distance = rate x time? Clearly, humans could and do live in the same environment that chimpanzees do and achieve far larger populations. In fact, one of the reason that chimpanzees might go extinct is human encroachment on the chimpanzee environment. That is classic Darwinian competition. So, how many beneficial mutations do you think it required for humans to get in this evolutionary position?

#17

We’ll see. Why don’t you see if you can find any error in that paper?

#18

Have you in fact submitted it to a legitimate, on-topic journal? What journal?

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#19

Because that’s how neutral evolution works, and the overwhelming majority of the mutations separating humans and chimps are evolving neutrally. Have you yet accepted that neutral evolution exists?

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#20

So, how many replications of a variant does it take to have a reasonable probability of a beneficial mutation occurring? If you have difficulty doing that math, I can show you how to do it. If you want to see an evolutionary experiment that demonstrates this process, watch this video:

Try to explain how this evolutionary process is working.