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What Home Looked Like For Seven Million Years - Comments

Neodarwinian's Avatar Comment 1 by Neodarwinian

Four times more efficient to walk than knuckle walk. Wonder how that stacks up, walking that is, against other forms of locomotion. Flying, swimming, snake like crawling and the like.

Sat, 06 Aug 2011 22:52:20 UTC | #858754

Anonymous's Avatar Comment 2 by Anonymous

Comment Removed by Moderator

Sun, 07 Aug 2011 01:23:44 UTC | #858773

epeeist's Avatar Comment 3 by epeeist

A timely reminder that all our theories are both tentative and provisional. Also that we should attempt to realise what our implicit assumptions and biases might be and try to minimise them.

Sun, 07 Aug 2011 08:39:51 UTC | #858813

Alan4discussion's Avatar Comment 4 by Alan4discussion

This carbon dating of residues in soils looks to have great potential in tracking historical changes in ecosystems.

Here is a very useful link I have put on earlier discussions of human migrations - http://essayweb.net/history/ancient/prehistory.shtml

Sun, 07 Aug 2011 09:03:42 UTC | #858815

cyberguy's Avatar Comment 5 by cyberguy

Comment 1 by Neodarwinian :

Four times more efficient to walk than knuckle walk. Wonder how that stacks up, walking that is, against other forms of locomotion. Flying, swimming, snake like crawling and the like.

We looked this question in Stage 1 Uni Physics many years ago.

Physics Fun Fact #1 - The most energy-efficient form of animal locomotion is that of a horse walking (True) Physics Fun Fact #2 - The second most energy-efficient is a human walking (True). Physics Fun Fact #3 - By using a bicycle, a human becomes more energy-efficient than a horse (True).

Logical Conclusion - The most energy-efficient combination is a horse on a bicycle! ;-)

Joking aside, I understand that humans can out-walk other animals, slowly chasing them to exhaustion and then killing them for food.

Sun, 07 Aug 2011 09:17:09 UTC | #858818

jcs's Avatar Comment 6 by jcs

@cyberguy (I understand that humans can out-walk):

This is especially true when it happens during the day in the bright sun.

The same also applies for dogs and cats chasing rabbits. Rabbits are more prone to overheating htne cats and dogs.

Sun, 07 Aug 2011 10:53:17 UTC | #858834

gordon's Avatar Comment 7 by gordon

I've tried outwalking our dogs. Never worked.

Sun, 07 Aug 2011 13:42:24 UTC | #858856

DavidMcC's Avatar Comment 8 by DavidMcC

Hominids have only been savanna-adapted for about 2.5MYr. Then the question is, why was Ardipithecus kadabba bipedal in a moist forest? Also, why do we need artificial water containers and bows and arrows (neither of which were available at 2.5MYa) to survive on the savanna?

EDIT: "Lieberman suggests that the earliest hominins adapted to the margins of those early forests, where they had to travel further from tree to tree to find fruit. "

Why go to the margins if you still had the forest itself, just like before?

Sun, 07 Aug 2011 15:17:33 UTC | #858869

God fearing Atheist's Avatar Comment 9 by God fearing Atheist

Comment 8 by DavidMcC :

Why go to the margins if you still had the forest itself, just like before?

I'm probably talking bollocks, but suppose there are areas of forest, open woodland, and savanna, supporting one species of ape. The area is vast (central Africa), and they are territorial. The evolutionary pressure on forest dwellers is for climbing, the evolutionary pressure on open woodland dwellers is to more from food source to food source with minimum energy. While the populations might interbreed at the margins, they are pulled in opposite evolutionary directions by their environment. Eventually that pressure, or other events, causes speciation. After that both species go their own evolutionary ways. Homonids who try and move back into the forest were out competed by other apes who climbed better. Once partially adapted to a niche (and partly unadapted to a previous niche), a sub-species is stuck.

I think this is the similar to the speciation of Galapagos finches - one initial population speciated because of adaptions to different food sources.

Sun, 07 Aug 2011 15:51:45 UTC | #858874

UGene's Avatar Comment 10 by UGene

Unfortunately for science, no one in Europe or the US is willing to talk about the evolutionary legacy we carry from our newer home, the temperate forests of Europe, with its dark, cold winters and cloudy days. We Europeans are no longer suitably adapted to an African savanna-environment. Our lighter skin evolved precisely to absorb more vitamin D from the sparse sunlight. Blue and green eyes may also have to do with the influences of the European environment, or at least with sexual selection restricted to our race only - no other race on Earth evolved these kinds of eye colors. We share a small amount of Neanderthal DNA (which presumably provides some adaptations to a colder climate), while Africans don't. They are the original Homo Sapiens; we are a genetic offshoot of the original humans, as are Asians, Australoids, and Amerindians.

It is truly fascinating to contemplate the diversity of mankind, yet some involved in politics would rather want to eliminate this diversity, if not physically than at least in intellectual discourse. We are all unique, and the environment in which our ancestors used to live millenia or even just centuries reflects itself in our genotype and phenotype.

Sun, 07 Aug 2011 16:02:19 UTC | #858878

DavidMcC's Avatar Comment 11 by DavidMcC

GfA, there are any number of hypotheses, but there isn't enough evidence that distinguishes them. I still prefer the one that syas that Ardipithecus kadabba was more adaptable than just being able to walk - he could wade as well. Why wade? Because of flooding events in NE Africa, which probably included the below-sea-level Afar depression. It is known that forest apes like orangutans react to flooding by talking an interest in the fish at the water's edge. (See the TV series, Orangutan Island.) Thus, the article is being too restrictive, IMO, in its scenario to cover millions of years of geology in what was, after all, a more volcanic region than it is now.

EDIT: Volcanoes can be bad for fruit yields, but are less bad for sea-food.

Sun, 07 Aug 2011 16:09:05 UTC | #858879

Bobwundaye's Avatar Comment 12 by Bobwundaye

I really like the theory that has been floated around for the last few decades that we actually developed in a very wet habitat. This could give rise to bipedalism since we'd have to keep our heads above water. It'll also explain why babies can naturally swim.

Also, (and please correct me if I am wrong but this is how I remember reading it) we are the only one of the whole group of chimpanzees, orangutangs, gorillas, etc. with a layer of fat directly under our skin, which is very useful in maintaining our temperature in water. Oh, and the fact that we lost our covering of hair on our bodies also seems to point in that direction, since it makes us more dynamic in the water and once out of water we dry of more quickly allowing for better temperature regulation.

Sun, 07 Aug 2011 16:50:51 UTC | #858889

DavidMcC's Avatar Comment 13 by DavidMcC

... Furthermore, it is both easier and psychlogically more comfortable for a forest ape to stay under the canopy and wade, rather than walk on terra firma away from cover. Thus, wading would likely have come before walking.

Sun, 07 Aug 2011 17:06:49 UTC | #858890

JuJu's Avatar Comment 14 by JuJu

Comment 12 by SpirituallyAtheist

I really like the theory that has been floated around for the last few decades that we actually developed in a very wet habitat. This could give rise to bipedalism since we'd have to keep our heads above water. It'll also explain why babies can naturally swim.

Also, (and please correct me if I am wrong but this is how I remember reading it) we are the only one of the whole group of chimpanzees, orangutangs, gorillas, etc. with a layer of fat directly under our skin, which is very useful in maintaining our temperature in water. Oh, and the fact that we lost our covering of hair on our bodies also seems to point in that direction, since it makes us more dynamic in the water and once out of water we dry of more quickly allowing for better temperature regulation.

This is called the Aquatic Ape Theory, and it doesn't hold up under scientific scrutiny. Human infants will drown if left in the water because they can't swim. The motions that people claim are swimming are really just reflexes that are shared by almost all infant mammals when put in the water. The subcutaneous fat idea is really a none issue. Its our diet and lifestyles that allow us to have noticeable fat, when a chimp eats a rich diet and doesn't exercise they get fat also. As far as being hairless and that allowing us to be dynamically efficient in the water, well, thats not true, humans are slow and awkward in the water compared to all other animals that actually did adapt to life in the water.

The theory is full of pseudoscience and I strongly recommend that you read over this blog Aquatic Ape Theory- Sink or Swim it is full of scientific scrutiny of the theory. I spent about a week looking over this theory from both sides, and I found that its full of logical fallacies and conspiracy theories.

Good luck.

Mon, 08 Aug 2011 05:27:00 UTC | #858998

Southpaw's Avatar Comment 15 by Southpaw

JuJu, you took the words right out of my mouth. AAH is nonsense.

Mon, 08 Aug 2011 06:33:06 UTC | #859009

DavidMcC's Avatar Comment 16 by DavidMcC

Juju, Southpaw, you are, of course entitled to your opinion, as is the author of the blog you link. However, you are being a little selective with what is and isn't evidence. It's a matter of interpretation. Further, the blog also explots the several errors that Morgan made to discredit anything that invokes something other than grassland. The worst effect of her interventin was to get the entire paleoanthroplogical community's back up - she HAD to be proved wrong at all costs.

There are also many versions of the "AAH", and (IMO) most of them are wrong, too. However, the idea that early bipedals just ignored water when it would have brought them food during a flooding event is a little hard to accept, given the known behaviour of orangutans and the known significant differences between NE Africa now and at 6-3MYa (something the title of the article blatantly ignores.)

Mon, 08 Aug 2011 08:16:58 UTC | #859018

Alan4discussion's Avatar Comment 17 by Alan4discussion

Comment 11 by DavidMcC

GfA, there are any number of hypotheses, but there isn't enough evidence that distinguishes them. I still prefer the one that says that Ardipithecus kadabba was more adaptable than just being able to walk - he could wade as well.

The National Geographic article associated with the diagrams (linked below), suggests Ardipithecus sediba, as a possible Homo ancestor.

Here is a diagram of the family tree of "Homo" with the prevailing view of the ancestry of humans, and a proposed alternative view from an associated article. - http://ngm.nationalgeographic.com/2011/08/malapa-fossils/lineage-graphic

With a graphic reconstruction of body-form here:

http://ngm.nationalgeographic.com/2011/08/malapa-fossils/hominid-graphic

Mon, 08 Aug 2011 08:22:45 UTC | #859019

Graxan's Avatar Comment 18 by Graxan

Natural selection exists because the environment is kinder to some individuals than others.

Hmm isn't this backwards? Isn't natural selection based on the organism's ability to adapt to different environments, not the fact that the environment has mood swings.

Mon, 08 Aug 2011 09:03:15 UTC | #859025

DavidMcC's Avatar Comment 19 by DavidMcC

Comment 18 by Graxan :

Natural selection exists because the environment is kinder to some individuals than others.

Hmm isn't this backwards? Isn't natural selection based on the organism's ability to adapt to different environments, not the fact that the environment has mood swings.

No, changing environments are a key driver of evolution. Individuals always try to follow the envrinment that suits them best. It's only when they can't follow the environment for some reason or other that selection produces phenoypic change instead of just genetic drift.

Mon, 08 Aug 2011 10:12:31 UTC | #859039

DavidMcC's Avatar Comment 20 by DavidMcC

Alan, A. sediba dates only to about 2MYa, so is not at issue for me. In fact, I wouldn't have an issue with this article if it was not for the "our home for 7 million years" bit. If it read "2.5 million years" it would be OK, AFAIAC.

Mon, 08 Aug 2011 10:17:58 UTC | #859041

DavidMcC's Avatar Comment 21 by DavidMcC

Also, Alan, there may have been any number of candidate evolutionary trees for the hominids of the last 6MYr, but, without genetic data, no-one can be confident of which is the best. Remember the debate about whether we evolved from the gracile or the robust australopithecines?

Mon, 08 Aug 2011 10:42:51 UTC | #859045

DavidMcC's Avatar Comment 22 by DavidMcC

From Alan's tree link:

The origin of Homo is a dimly understood stage in our evolutionary journey, and the view that A. sediba is the ancestor of our genus will not go unchallenged.

That's one thing that we can all agree on, I'm sure!

Mon, 08 Aug 2011 11:34:06 UTC | #859050

Alan4discussion's Avatar Comment 23 by Alan4discussion

Comment 22 by DavidMcC

That's one thing that we can all agree on, I'm sure!

Having said that, it's still good to have some clear, concise, if somewhat simplified illustrations, as easy reference to help with the discussions.

Mon, 08 Aug 2011 14:07:14 UTC | #859104

JuJu's Avatar Comment 24 by JuJu

Comment 16 by DavidMcC

Juju, Southpaw, you are, of course entitled to your opinion, as is the author of the blog you link. However, you are being a little selective with what is and isn't evidence. It's a matter of interpretation. Further, the blog also explots the several errors that Morgan made to discredit anything that invokes something other than grassland. The worst effect of her interventin was to get the entire paleoanthroplogical community's back up - she HAD to be proved wrong at all costs.

And you are entitled to your own opinion, but you're not entitled to your own facts. The claims made by Elaine Morgan et al have been looked at though the lens of science and they simply don't hold up. The conspiracy theory is that scientist had to prove her wrong at all cost, which isn't true. She's the one making the claim and she must provide the evidence to back it up.

There are also many versions of the "AAH", and (IMO) most of them are wrong, too. However, the idea that early bipedals just ignored water when it would have brought them food during a flooding event is a little hard to accept, given the known behaviour of orangutans and the known significant differences between NE Africa now and at 6-3MYa (something the title of the article blatantly ignores.)

I can't think of anyone who claims that early bipedal primates "just ignored water", thats a strawman and not positive proof of the theory, as a matter of fact you haven't shown any evidence whatsoever. I looked deeply into this debate looking at all the available evidence and came to the conclusion that the theory as written by Elaine Morgan herself, not some other version, is nonsense. And as time goes by, in order for the theory to seem plausible and to save face, all sorts of logical fallacies have been used and science has been subverted.

Mon, 08 Aug 2011 15:43:41 UTC | #859125

blitz442's Avatar Comment 25 by blitz442

Bah! That looks absolutely nothing like a garden with a talking snake.

Mon, 08 Aug 2011 23:58:02 UTC | #859285

DavidMcC's Avatar Comment 26 by DavidMcC

Comment 24 by JuJu

I looked deeply into this debate looking at all the available evidence and came to the conclusion that the theory as written by Elaine Morgan herself, not some other version, is nonsense.

I think it's wrong, too. She emphasised motherly care for the infant, whereas I emphasise the exploitation of all food sources in an unreliable environment.

And as time goes by, in order for the theory to seem plausible and to save face, all sorts of logical fallacies have been used and science has been subverted.

Sounds just like savanna theory. You might not be referring to every version. For example, the first "A" should stand for "amphibious", not "aquatic", which is a straw man.

As you admit, early bipedal primates would not have ignored water. All I am saying is that that had consequences - it is not a trivial admission, because of the importance of water. One aspect of my version of the amphibious ape is that the very first such apes had discovered food in water that came to them, in a forest flooding event. From then on, as they were likely short of food generally. they would associate water with food in a way that no forest ape had done before. Being social animals, they then incorporated that association in their group culture. The evidence for this is clear in ourselves (as I posted above) and in the behaviour of forest apes in the unusual circumstances of "Orangutan Island" (again, as above), and to some extent in the geological history of NE Africa, thought the latter is not known in sufficient detail. Most ant-AAH just look at bones and savanna aspects of our traits, not realising that they are the compromises between savanna and water that you would expect of an amphibious ape.

Tue, 09 Aug 2011 09:40:16 UTC | #859366

DavidMcC's Avatar Comment 27 by DavidMcC

... In some ways, we are the elephants of the ape family.

Tue, 09 Aug 2011 09:58:26 UTC | #859370

JuJu's Avatar Comment 28 by JuJu

@ DavidMcC

Just because there were floods doesn't mean that apes became "amphibious". What exactly are you suggesting they changed their diet too?. And what evidence do you have? Why wouldn't they just have stayed out of the water and continue on with their more traditional diet. In your "version" which I think sounds as highly implausible as all others, it would seem that virtually any animal that lives in an area that may become flooded on occasion must become "amphibious", that would be a bit of a slippery slope. As far as a change in phenotype, which is suggested by the AAH, it would take natural selection working on the apes, the ones that had the lucky mutations that gave them the ability to survive in the water would survive and the ones that didn't would have died. The more plausible idea and the one more closely fits the evidence is that the ones that figured out how to continue to survive out of the water would be more likely to have survived and any that were left to fend for themselves in the water would have died (crocodiles anyone?) (water born pathogens?). If you think that the occasional crossing of water or drinking from a water source makes you "amphibious" then almost every animal in Africa is amphibious.

The reason I started looking into this debate was because a friend of mind suggested that the reason humans are hairless is because of this "aquatic past" that I had never heard of. He even went on to say that women and children are less hairy because they spent more time by the water then did the men who were out hunting, as if the water somehow made them "softer". Once I looked into it and explained to him how natural selection actually worked, and explained that the AAH is just a wild guess based on incorrect correlation and causation, and doesn't fit with any of the evidence we have so far. He told me how he thought evolution worked and recited perfectly the Lamarkian view of evolution. When I explained that this had been debunked over a century ago, he claimed that science doesn't know everything and that there is a "environmental force" that goes through your skin and twittles with DNA to make you fit into the environment where you happen to be living at the time.

Arguing with someone over the AAH is like arguing with a alt/med proponent or creationist, it drives me crazy. They believe in the theory so much that they misinterpret, make up, and cherry pick evidence to make it seem plausible.

Tue, 09 Aug 2011 14:58:56 UTC | #859427

DavidMcC's Avatar Comment 29 by DavidMcC

Juju, I mentioned elephants, not "every anmial in Afrrica", as being amphibious in a roughly analogous way to us. For the puroses of this thread, forget about the panoply of other "AAH"s in this thread, and what your friend said. My AAH is based on what I described in posts above, concerning the period of geological instability in NE Africa leading to floodings, ... forest apes finding that there are edible gastropods in the water... changing their culture to adapt to that...

You don't seem to be listening.

As for plausilibity, it's as plausible as an elephant.

Wed, 10 Aug 2011 11:00:17 UTC | #859634

DavidMcC's Avatar Comment 30 by DavidMcC

... Also, I am not suggesting a total diet change to gastropods only for all generations of the ancestral apes. The extent of reliance on these would obviiously vary according to circumstances, but there must have been periods of severe damge to forests that forced some generations to rely on the slugs and snails cuisine for a while, as they might have been more reliable than fruit at times- often enough, perhaps, for the apes to wade to get them.

BTW, I mention gastropods because these are known to have existed in some abundance at the time and place of the appearance of Ar. kadabba (though I can no longer find the reference - I posted it on the old RD "evolution" forum, but didn't keep it for myself.

I suspect that you believe pure savanna theory so much that you don't see its weakness, such as the "elephant" in us. (Elephants also like a "holiday by the sea" from time to time!)

Wed, 10 Aug 2011 11:15:36 UTC | #859638