h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Roll up, roll up. Come on in ladies and gentlemen, and view the eighth wonder of the world: Aqua Man!

Why are we crap swimmers then? Is there any aquatic or semi aquatic animal which is as awful as we are at swimming? Plus, we must be the only aquatic animal that has to be taught to swim. (Alright, you could swim when a baby, what's the swimming instructor going to say 'Take a deep breath and remember how'?) Even non-aquatic animals like dogs and cats can swim.

Body hair: most aquatic mammals seem to either have no body hair (whales etc.) or plenty (otters & co.). Why would we be in this awkward half-hairy/half-bald stage? Is this some intermediate stage in becoming "Aqua-Man"? (coming soon to a cinema near you!

Why aren't our fingers webbed? It would seem to be a mere bagatelle compared to the other adaptions mentioned in the article and in the posted comments. I mean, it is a bit obvious isn't it? Should be easy too, apparently we manufacture skin cells between our fingers naturally, but they are killed off at a certain stage in accordance with the DNA masterplan.

If we did evolve at least partially in a sea-salt aquatic environment, then why does it hurt to open my eyes under water? We can't use our sense of smell when submerged, and hearing goes all funny (rivers tend to be noisey anyway, as does the sea), so surely sight would become an evolutionary imperative for an aquatic human?

Our subcutaneous fat isn't enough to keep us warm in an aquatic environment. Try it for yourself. A couple of hours in the surf in Britain or Ireland will have you shivering. This is ok as long as this phase in our development took place in Africa were presumably the water is 'nicer' than the freezing stuff we get in our neck of the woods. But wait a minute, aren't there crocodiles in Africa? And we are crap swimmers as mentioned above. Damn dangerous evolutionary niche to get into, if you ask me!

Nice left-field idea though. If I was back in school I'd torment my science teachers with that one

This theory makes intuitive sense, but I'm not sure how much farther it goes from that.

All of the (totally valid) criticisms that you raise Maolmuire can be explained with one part of this theory: That we were *once* semi-aquatic, but have since evolved back into land-inhabiting creatures.

- We are crap swimmers because we have found huge evolutionary benefits from bipedal locomotion (freeing up hands, communication, etc.)?

- We lost all our hair in the water and since re-found it's warmth-giving qualities?

- As you pointed out, our fingers are webbed in the human embryo, but programmed cell death gets rid of them. That is quite a simple genetic switch (which of course leads to more complex downstream effects).

- Eyesight, I'm sure one could "get used to" salty water, maybe no genetic adaptation would be necessary. As for the rest of the senses, this is a very good criticism. Perhaps we have some latent sonar we don't know about!

- Living in America, I have witnessed enough subcutaneous fat, some on myself. Fish are fatty and yes, African waters would be warmer.

Though valid logically, I'm not sure all of my above suggestions would get into a scientific journal. I'm off to search some journals (using my work subscriptions!) to find any stuff on this fascinating topic.

Nice to see some good criticism by the way , this theory is not without it's flaws.

Ste

I agree, there *are* holes in this theory. The main reason for mentioning it is as an antidote to the all-powerful down from the trees and onto the plains model.

But to actually address your points:
We don't need to be taught to swim. My cousins have never had a swimming lesson in their lives. All were introduced to water at a very early age, before they could speak, and just swam naturally. They've never not known how. But, as you say, instinctive swimming is common to dogs, cats, and other non-aquatic animals, so it's not a great piece of evidence, really. The holding your breath thing is, though. Dogs, cats etc. can't think "right, I'm diving now", and just decide to stop breathing. We can, uniquely among land animals. Odd.

Body hair - we lost most of the hair to streamlining. The remaining hair, at least below the neck, is mainly about retaining pheromones (it all comes back to sex in the end! )

As Ste points out, webbed/not webbed is not a complex bit of evolution - there was a kid in my class at school who had webbed feet, and not just slightly either, completely webbed up. His hands were much more webbed than normal, too. Rare, but by no means unique.

It hurts to open your eyes because the salinity of the sea is greater than the salinity of your tears. This would not be the case in (a) a river or possibly even (b) the sea six million years ago. The sea *is* getting saltier. Your hearing goes "all funny"? You can still hear stuff. What's funny about it? (Serious question - I think hearing is the sense *least* affected underwater). And you most certainly can smell underwater, it's just that (a) our sense of smell is very poor anyway and (b) most of us don't go near anything smelly underwater. I've read anecdotes from wreck divers who've opened sealed barrels of pork on Tudor warships, and they report being knocked sick by the smell of the rancid meat in the barrels.

As for a couple of hours in British surf without a wetsuit - are you mad!? A couple MINUTES is enough for most! But as you say, the theory still posits origins in Africa, where it is HOT, and the cool of the water would probably be blessed relief. And yes, there are crocodiles, and hippos too, nasty aggressive fat things with teeth the size of your forearm that kill more people per year than lions. But there are also lots of other animals which live and around the water, and sure some of them are killed and eaten, but most survive. The presence of predators doesn't make life impossible, just more, ah... "interesting".

Thanks for reading and commenting! It's great to get feedback, and thoughtful, insightful and reasoned feedback is even better (rare as it is )

Thanks

H.

The original paper is entitled "On Weighting and Congruence" (1996) by Marc W. Allarda and James M. Carpenter in the journal "Cladistics",
Volume 12, Issue 3, Pages 183-198.

It is a study of mitochondrial DNA (mtDNA, maternally inherited and not subject to recombination during mieosis, so it's good for evolutionary studies). It wasn't setting out to prove any outlandish hypothesis or anything, it was a paper that was suggesting ways of making cladistics and phylogenetics less subjective. During the study they made evolutionary trees of relatedness from the mtDNA and tried various different weightings to see the outcomes.

One of the outcomes was that humans appeared closer to the blue whale and the grey seal.

However, it seems like the mtDNA samples got mixed up! There are numerous critiques of this paper that reference their original, erroneous data with the updated correct data for independant comparison. It seems like thier whale DNA was human DNA, their grey seal DNA was whale DNA and their horse sequence is actually harbour whale DNA. This would explain a lot.

One paper goes further to also criticise the anatomic arguments (which do seem at first quite compelling). It is "Comments on Allard and Carpenter (1996), or the "Aquatic Ape" Hypothesis Revisited", by Roderic D. M. Page and Michael A. Charleston in Cladistics, Volume 15, Issue 1, Pages 73-74. These are really too numerous to summarise.

"Cladistics" can be found at http://www.cladistics.org/journal.html, you will need a subscription of pay a one-off fee to read these papers if you don't have access to a library or university/work subscriptions.

It looks like the Aquatic Ape Hypothesis might be a flash in the pan. Erroneous data produced some suprising results which were published. Those data were discovered faulty and the community responded.

I still like the hypothesis though. Perhaps this is why it never made it past the "hypothesis" stage...

Shame .

Ste

Sorry, it wasn't the *original* paper, just one that resurrected the debate. I have just reread the entry and found that I had forgotten that Hardy in 1960 first came up with the idea.

Having looked around the net and looked further into the aquatic ape thing it begins to look more and more believable. Here's a quote (http://www.geocities.com/Athens/5168/aat/leaflet.html)(url may be moderated): "Lucy's [australopithecus afarensis] bones were found at Afar lying among crocodile and turtle eggs and crab claws at the edge of a flood plain near what would then have been the coast of Africa." Okay, she could have been on holidays at the beach (but no fossilised bucket was found ), or maybe it was her natural habitat?
Perhaps streamlining would also explain what happened to the opposable thumbs on our feet (I miss them anyway!).
One thing which does still cause a frown to furrow the brow: since it is generally accepted that the appearance of modern humans was a bit of evolutionary speeding (cutting the deck, so to speak rather than dealing off cards one by one to reach the desired position), how likely is it that this sort of thing occurred twice within a relatively short time frame?

In any case, the aquatic ape theory seems to have given the generally accepted savannah theory a kick in the backside which can hardly be a bad thing. It is making people look twice at what they believe and the conclusions that they have drawn from the available evidence.

Cheers!

Chin up Ste! Just because it mightn't be entirely true, doesn't mean to say it doesn't have some validity! After all, the savannah theory has gaps in it too, like the apparent lack of trees of sufficient size to provide shelter to early humans 5-7 million years ago in Africa. So I say 'Onward!' to Aqua Man!

Right, I'm off to the bath to practice!

One thing I haven't seen mentioned yet is our attraction to water.

Humans enjoy bathing, has anyone ever tried to wash a pet cat or dog?
We find lying in water very theraputic and relaxing.
We swim for pleasure. Why else would every town have a public swimming pool?
We feel safe living next to rivers and seas. Nearly every major city in the world is built next to water.
We keep fish for pets. We enjoy watching our aqautic cousins.
We build ponds in our garden. Why? Unless some instict tells us it's good to be close to water.
We go fishing for pleasure. Why do some people get up at the crack of dawn to sit by a cold river bank, and put back anything they catch?

There's surely some link in our past to water.

>Humans enjoy bathing, has anyone ever tried to wash a pet cat or dog?

Small problem- it may be Hell to get a dog to stay in the bath (believe me, I know), but when presented with a river or lake, 75% ish of dogs will take one look and rush in.

Yeah I did think of that, and then thought how much cats hate all water.
So perhaps aqua man used domesticated dogs to help him catch fishand stuff, and it's now part of the dogs instict too ?????

Not all cats hate water either- although most of the cats I know won't go out in the rain, they *will* jump into water-butts and the like.

A decent site on the many ways Aquatic ape proponents abuse science:
http://aquaticape.topcities.com

It could of course be false, but at least it includes information making it possible to do so.

Although the main point of this entry is true, scientists are in many ways too closeminded and willing to ignore evidence that opposes their views this seems to go doubly for those proposing the Aquatic Ape proponents.

your right about aqua-ape it just had to be,who says ape-man couldnt discover fish? their high in protien and is good for a developing brain so is learning new skills (fishing/swimming).modern apes cant swim at all they just sink but they can walk on two legs when wadding through water because it helps to support/balance them (interesting?).
the reason we are half hairy could be due to only loosing body hair when we started wearing clothes to migrate north?
as to why we cant all swim without havin to learn? dont we have to learn how to walk/talk...climb trees even?

A further extension on the above....

As I understand it there is an oil present in fish vital to the development of brain matter. If what I have heard is correct it explains how life can get so massive in the oceans with many creatures with such massive brains like the whales and dolphins.

To come back to man - I have also heard that 1% of the present population are unable to synthesis this chemical. If this is true, and we assume our ancestors had a similar deficiency in the population - effecting a similar proportion of the population, then evolution may well have selected in favour of populations capable of securing external supplies of this substance - fish.

Of course this is still just speculation.

If hairlessness came from moving north, than how come those groups, like the bushmen, than never left Africa don't have hair?

Why we lost our body hair.

Homo Ergaster (1.8 MYA- 1.5MYA) had loss a major proportion of the body hair of the previous Australopiths and Homo speices. This was due to having to deal with African savannah heat. Sweating is a much more effective cooling system than panting. Panting is the system hairy animals use to reduce heat, as they can't sweat. Too many hair follicles on the skin to allow for sweat glands.
Do aquatic animals have problem with heat reduction?


Fish oil good for big brains.

Yes it is, but the shellfish are as well. Ancient human habitations have been particularly in South Africa that would seem to imply from the tool types that certainly Homo erectus ate shellfish on a regular basis. But fish oils are not the only source of proteins that are beneficial to large brains. Bone marrow is also a good source. Plenty of animal carcasses have been found where the bones have been smashed open to allow Australopiths (Homo Habilis (1.9-1.6 million years ago) access to this rich food source.

As was noted by some scientist, our feces' water content is far more typical of a marine mammal than it is of a savannah-dweller. A semi-riparian or marine past becomes more and more convincing when you compare the characteristics of the predatory mammals who actually inhabit these environments:

Savannah: hairy
Marine: not hairy
S: not fatty
M: fatty
S: very low water content in feces
M: very high water content in feces
S: not instinctive swimmers
M: instinctive swimmers
S: reasonably intelligent
M: very intelligent
S: no 'language' aside from some grunts, growls, & calls
M: language
S: walk on all fours
M: do not walk on all fours (most don't even have 'fours')

Peace

Those are pretty tenuous at best. You're comparing traits with not-having-traits, which is akin to trying to prove a negative.

Ste

Comparative anatomy contrasts what one creature has versus another. For example, one is tall or short (not tall); one's skin has loads of melanin, another's has none. It's amazing that one unprovable theory versus another unprovable theory is so fraught with detractors - - - it brings to mind the lady protesting too much (or is it too loudly?) How would modern anthropologists be harmed by a marine or riparian genesis?

Hugs, not Bugs

"Comparative anatomy contrasts what one creature has versus another."
My point exactly. You cannot compare one trait with not-having-a-trait. With comparative stuff you have to have things to compare! Savanna-dwelling mammals don't enter into it in your above examples.

However, it's interesting that you chose animals that roam savannas. Because the opposite of what you say is actually the truth:

Recent phylogenetics (from fossil, DNA and morphological comparisons) have shown that Cetaceans, whales, dolphins and other marine mammals, are very closely related to the Artiodactyla, which include pigs, cows, camels, hippos (notably a semi-aquatic mammal), giraffes, gazelles, warthogs (the last three are savanna-dwelling mammals. Humans are nowhere near these guys. http://www.museums.org.za/bio/mammals/cetacea/

Look at this tree, see how closely the artiodactyla and cetaceans are together compared to the primates: http://users.tamuk.edu/kfjab02/Biology/Mammalogy/Mammal_classification.htm

For a REALLY, REALLY detailed link see this: "The Emergence of Whales" http://home.tiac.net/~cri/2001/acker00.html

Any superficial resemblences we have to marine mammals are just that. The evidence for whales, etc. coming from cloved-hooved land mammals is overwhelming.

One of the main problems with the aquatic-ape hypothesis is that its author (forgotten her name) doesn't seem to want to listen to such evidence. That isn't good science



Ste