Re: Morgan and creationists

Paul Crowley (
Sat, 06 Jul 96 00:06:10 GMT

In article <4re67n$> "HARRY R. ERWIN" writes:

> 1. I rule out intertidal foraging because that is usually associated with
> shell middens. We find those going back perhaps 100,000 years in Africa
> and 60,000 years in New Guinea, but no further.

Middens will be found above sea-level only on geologically raised
coastlines. I understand that very few of those in South Africa
have been accurately dated. It is unlikely that, prior to hss and
the regular use of fire, hominids could have permanently inhabited
oceanic coastlines. They would have been too exposed to nocturnal
predation. They needed an inland sea, with relatively small tides.
This means a small and highly localised population - exactly what
is needed for the rapid evolution that we know took place. There
may be middens there >100 Kya, or they may be under the sea or they
may have been consumed by coral.

> Besides, intertidal foraging is an easy behavioral adaptation and
> could have been gained and lost many times.

I would strongly disagree with your "easy behavioural adaptations".
Once a species has found a modus vivendi it's not going to abandon
it. And hominids are no exception. Hell, hss is no exception.
The examples of modern human populations going extinct because
they could not adapt to change are too numerous to list -- changes
in climate or especially from contact with other (usually Western)
cultures. My own belief is that *IF* hominids adopted intertidal
foraging around 5 mya, they never abandoned it (ok, so most took up
farming about 10 kya).

> Since it seems to take several million years to develop
> the ability to drink saltwater, any intertidal foragers in the hominid
> ancestry had to maintain terrestrial behavior.

No one has ever doubted that all hominids have always needed fresh
water. Your strawman is far too weak.

> 2. Yes, I'm setting up a strawman ("null hypothesis") to gain an
> understanding of how it can be falsified. That's what scientists do. It
> can't be a weak strawman, though, or it doesn't rule out the interesting
> cases.
> : In any case, you are engaged in a deeply fundamental exercise of
> : self-deception. You have not got a working/alternative hypothesis.
> : Or if you have you are not willing to subject it to the same sort
> : of tests. Without one, a null hypothesis has no function.
> You misunderstand. Read Popper. I do have a number of working hypotheses,
> but I can't judge their validity until I've tested enough null hypotheses
> to narrow things down quite a bit.

Setting up, and then knocking down, a number of far-fetched strawmen
is not going to help at all. But the problem is much deeper. It's
fine to have null and working hypotheses about a problem that can be
clearly stated (such as *perhaps* the origin of bipedalism). However
the problems of hominid evolution are nowhere near that stage. The
ecological niche(s) occupied by early, middle or late hominids has
(have) not been identified. There are no accepted theories. What
little consensus exists is in a state of a constant flux. You are
discussing mountain-formation without a theory of plate tectonics;
you are considering pluvial deposits without knowledge of Ice Ages.
Your posing of null hypotheses is equivalent to pretending to do an
accurate survey of a site with the latest theodolite *in_a_dense_fog*.
That is what I meant by "self-deception". The current state of
knowledge is not appropriate for such techniques.

> : "The lineage leading to H. sapiens experienced a phase extending over
> : three chronospecies during which it was adapted to woodland foraging
> : behavior." ^^^^^^^^
> This doesn't work as a 'null hypothesis.' It's not probably false.

On the contrary, we know exactly how hominoid species can adapt to
woodland foraging; we know what fossils it leaves (i.e. none).
Hominids possess none of the relevant adaptations and have a
fossil record that is utterly at odds with that hypothesis.

> : "The lineage leading to H. sapiens experienced a phase extending over
> : three chronospecies during which it was adapted to littoral foraging
> : behavior." ^^^^^^^
> This is hard to falsify. Hence it is not a good 'null hypothesis.'

But it's got to be falsified if you are going to prove another one.
Being "hard" is no excuse for a scientist.

> : "The lineage leading to H. sapiens experienced a phase extending over
> : three chronospecies during which it was adapted to savanna foraging
> : behavior." ^^^^^^^
> The lineage leading to modern Homo sapiens has been adapted to savanna
> foraging behavior for at least 1.85 MYr. The direct evidence is the
> Nariokotome skeleton.

The line of reasoning is extremely weak. The lifestyle of the Masai
has little or nothing in common with that of hominids around 1.85 Myr.
And they don't forage on the savanna. Finding a "Masai-like" skeleton
is not evidence for savanna foraging.

> It's easier and more scientific to answer the following questions:
> 1. What food did it not eat?
> 2. What nocturnal refuges did it not use?
> 3. What tactics did it not use to avoid predators while foraging?

I'd have only a limted agreement here. The steady and persistent
change in dentition showed a movement away from a woodland-type
diet. The whole morphology and especially the bipedalism shows
that it could not have slept in the trees. But I'd disagree with
your "more scientific". At some point you have to present a whole
scenario which hangs together and works. You can show that the
structure of DNA is not X, or not Y, or not Z; but at some point
you have to come out with a positive hypothesis and say that it's
a double helix -- and then prove it.

> The following is a working hypothesis. The most obvious way bipedalism is
> advantageous (given the quantitative studies on locomotor efficiency) is
> sensory. You can see further in environments where you have to move on the
> ground if your eyes are far off the ground. That means you can move
> further away from a tree on the ground and safely get back. That means you
> have a selective advantage over knuckle-walkers in the _forested_-savannah
> biome.

This used to be one of the arguments for bipedalism on the savanna.
I always found it incredible. Nothing could be more obvious to a
predator than heads bobbing along above grass in the middle or
far distance. Soldiers on patrol progress in a crouched or prone
position if they think the enemy might be in the vicinity. Maybe
one of them stands up gingerly on watch while the others crawl away
or into position. But quadrupedal chimps can do that too. They can
perform every aspect of the operation (the watching and the moving)
faster and more effectively than a bipedal creature. The selective
advantages are all against the bipedal animal.

> By the way, complex ecosystems (the ones that survive as an ecosystem for
> long periods) are characterized by multiple ecological vicars. More than
> one species in the system can make use of a resource. That implies the
> hominid ancestor had such vicars prior to the invasion of the littoral.
> When it did invade the littoral, it would have been accompanied by some of
> its vicars. What happened to them?

I don't know what you mean by "vicars". Whatever it means, I feel that
you are over-applying some general rule. We are only talking about one
species that we know exploited a resource in the recent past. You may
say that past is probably only 100 Kya, I may say it's probably 5 Myr.
That's still recent.