Re: Look humans really are aquatic!

From: Jason Eshleman (jae_at_vici.ucdavis.edu)
Date: 12/28/04 

Date: Tue, 28 Dec 2004 08:07:23 +0000 (UTC)

Algis Kuliukas <algis@RiverApes.com> wrote:
>Philip Deitiker wrote:
>> "
>> [snip] It is not a conspiracy. When Philip has an idea it isn't a
>> mandate from hell that we all know or believe in it.
>> "
>>
>> Damn, I guess me and the other Illuminati will have to increase
>> the dose of mind controlling hormones that we put in the water.
>>
>> I wonder how many whales, sea otters, sea snakes and other
>> aquatic adapted animals were killed.
>
>I expect a significant number *were* killed but, of course, as no-one
>is suggesting humans were ever anywhere as aquatic as that, it's an
>irrelevant comparison.
>
>> To what Su said, according to the reports that is exactly what people
>> did, they climbed trees and ran for high ground.
>>
>> Or should I put it conversely.
>> If you are on a coastline with a very steep beach and a sharp
>> dropoff offshore, and by chance you suddenly see the ocean recede 10
>> or 20 feet in depth. That is a pretty good sign you should be running
>
>> like hell in the opposite direction.
>
>Of course. But tsunamis are hardly a daily occurrence, are they? I mean
>that would be like arguing that humans must have been aquatic because
>the rift valley is littered with volcanoes.
>
>The point of your sarcastic sneering posting to start this thread was
>to make some kind of comment that this disaster somehow made the
>likelihood that humans were more water adapted than our ape cousins
>less likely. That's just nonsense, Philip.
>
>Some of the key questions here are these:
>1) How many people that got washed up in the tidal waves actually
>survived?

This point is only important if the stimulus occurs in such a manner that
it is not essentially random with respect to the afflicted. *If* there is
a selective difference associated with some rare event, it is generally
weak selection. Note selection here is with regard to a heritable trait
that conveys a survival and/or reproductive advantage to those who possess
it. Note that even if the difference is life or death, if the stimulus is
rare, the overall selection will be weak. For instance, if there is some
trait that makes one 50% more likely to survive a tsunami (this would be
considered a rather extreme difference), the overall effect of selection
is dependent on the frequency of tusnamis. If they happened every
generation, the coefficient of selection against those without the trait
would be high indeed. If they are rare, occurring only once every 50
generations or so, the effective selective difference is going to be very
low though. The odds that the traits responsible will be lost due to
drift alone (ignoring any counter-selection) between the rare events
becomes increasingly significant. Effectively, the huge survival
difference becomes an increasingly negligible selective difference.

The actual probability that the alleles responsible for the selective
advantage will ever hit fixation rather than simply be lost due to drift
is equal to their effective selective advantage. This is an equation
independent of time. Arguments that over the course of evolutionary time
even the rare events will necessarily be selectively important are simply
not true. Some things that convey small advantages do reach fixation, but
most do not. Most disappear due to drift.

>2) How many survived because they were better swimmers than similar
>victims that didn't?

This point is important ONLY if there is some heritable difference
involved and even in this case, it becomes evolutionarily important only
if such situations occur with sufficient regularity such that other forces
do not counter the effects in between selective episodes.

The math is not really all that difficult and it's a whole lot more
informative than series of manipulated thought experiments with dubious
parallels in reality about drowning chimps and sweeping just-so stories of
human buoys. In this light, the just-so stories and amusing thought
experiements don't really matter much without some exceptionally solid
evidence that the scenarios were actually likely and common and the
survival differences actually pronounced.

>3) How many chimpanzees would have died if they'd have taken the place
>of the people touched by this disater?

A total unknown. If the key was an ability to climb and hold on, it may
well have been fewer than the number of humans. But since selection by
tsunami is a rare and unpredictable event that thus makes coefficients of
selection associated with the events as a product of the rarity of the
event, it's an almost completely moot point.

Relevant Pages

  • Re: Look humans really are aquatic!
    ... But tsunamis are hardly a daily occurrence, ... >>that would be like arguing that humans must have been aquatic ... Note selection here is with regard to a heritable ... > drift alone between the rare events ...
    (sci.anthropology.paleo)
  • Re: Is the AAH a legitimate hypothesis? Of course it is.
    ... The fact humans swim better ... >> chimps really must be due to natural selection because the weakest ... > history of chimps since the bifurcation of our lineages where in one ... > lineage increasing abilities in water led to greater survival. ...
    (sci.anthropology.paleo)
  • Re: Updated AAH Definition
    ... > the fervor with which Algis is confident that hominids were more ... > investigation for Algis (who seems to be on track to do research built ... > The prediction that humans swim better than apes isn't a prediction so ... > like the null to be that selection was responsible and put the burden ...
    (sci.anthropology.paleo)
  • Re: A critique of the BBC aquatic ape programme and the transcript.
    ... >> the context of a discussion about locomotion, ... Sexual selection? ... If it's humans, is it because we've had selection to move ... I take your point that chimps may have *lost* their ability in water, ...
    (sci.anthropology.paleo)
  • Re: Updated AAH Definition
    ... Because that was where you seemed to be heading in the debate before. ... > likely given the nature of the beast and the nature of the selection. ... modern humans do all of those things - you don't. ... through water than chimpanzees. ...
    (sci.anthropology.paleo)