Camaban

not sure whether this has been mentioned here or not, but wouldn't our relative baldness be more a result of starting to wear clothes to protect us from the elements? (The way I see it, having all that fur under a layer of protective clothing would be extremely unhygenic, and if we have no fur it's both easier to select how protected we want, and more hygenic, and clothing can be made much more efficient than fur anyway)

Jesus Tap-Dancin' Christ

Hippos actually are rather fast. Further, Olympians are not the norm for humans. They are people who have done everything in their power to excell at that one particular area.

Duvenoy

Thanks, Oolon.

I've read that Manatees and Dugongs were Elephant relitives, but never really considered the common ancestor. In fact, I've not thought much about it al all. Now, I'm curious.

Excellent paper!

doov

Duvenoy

Well, it looks like we've covered about everything but..... Diet.

If I may be allowed to speculate, and I will anyway, so don't bother to holler, it seems to me that, according to the fossil record, our ancestor(s) of 10 to 5 million years ago were much better equipped to forage ashore.

Consider, we and our ancestors are built somewhat like half a spider, not the best form for catching aquatic prey unless you happen to be an echinoderm. And I find it unlikely that they grazed on algae and kelp. On the other hand, grasslands could provide a diet that might be even more nutritious than our own, and easy to gather.

Insects and their larvae, roots and bulbs, lizards and snakes, tortises, small mammals, and, for an adventureous troop of proto-humans, a big cat might be harassed off it's kill. And, the odd, reasonably fresh carcass might be found.

AAH is a fun discussion, but in the final analysis, there's nothing there.

doov

Amen-Moses

Some points:

Humans that today live a semi aquatic existance (i.e south sea islanders etc) live almost exclusively on marine produce not only that but one of the few foods that we prefer to eat raw are marine produce (or river/lake) produce. Personally I hate things like lobster and crab but that's just me.

I can close my nostrils underwater and the aforementioned south sea islander also can to a greater degree, in fact the only races that cannot do so are those who have an extended history in dry inland regions (of course with disuse the ability fades but almost all young children can close their nostrils).

Humans are just about the best swimmers of all land mammals and only Elephants are known to swim further than humans from choice (i.e they have been known to swim between islands many miles apart) and as has already been pointed out they have an aquatic ancestor.

(the argument that olympic swimmers are in some way "special" avoids the obvious rejoinder that they are only special becasue they swim every day, if you had swum every day from birth you would be of similar ability)

Now I don't think (and I doubt any AAT supporter does) that humans ever had to compete in the open ocean with sharks or dolphins nor do I think that savannah supporters think that we ever went up against Lions and Cheetahs (in fact wasn't one of our main predators the Leopard? Not exactly the fastest or social of predators) or any of the other huge megapredators of a few million years ago (take a look in your nearest natural history museum if you don't know what I mean, 8 foot hyenas anyone?). Even modern humans living mainly around rivers in Africa deal with crocodiles so they aren't really such a big problem (at least they are totally predictable so with a little training are easy to fend off) so I am left thinking "where is the safest environment for hominids?", not in the sea, not on the savannah, not in the jungle (in competition with far stronger chimps), not in the mountain forests (in competition with other stronger and faster primates) but in the margins, i.e close enough to the water to dive in and evade land predators (and collect highly nutritous turtles, crabs and mussels) but close enough to a tree line to evade the odd crocadile (and to provide sticks with which to fend them off) or nasty snake.

That is how I think we became generalists, then later with climatic changes reducing the number of wet environments but at a time when we had already evolved tool making abilities and advanced social cooperation we spread (along rivers and coastlines) into drier environments in which those skills could now be used (in fact had to be used) to survive.

Amen-Moses

Amen-Moses

Hippos are actually damn dangerous to humans (I read somewhere that they kill more humans than do Lions) but nearly all that danger is on land, they can run extremely fast for short bursts and the only safe place is up a large tree. But regardless modern Humans and Hippos share the same parts of the river, why is that? (I'll give you a hint, Hippos hate Crocodiles and will attack them without provocation)

I even watched with interest a documentary where the adolescent boys were daring each other to leap onto full grown hippos, they then dived into the water and swam away when the Hippos tried to attack them (reminded me somewhat of the "train surfering" craze that killed so many kids here a few years ago).

Amen-Moses

Duvenoy

What land animals are better swimmers than humans? Oh my, lesse now:

Polar bears, Kodiak bears, monitor lizarsds, the larger iguanaids, any snake (rattlers have found at sea and have populated several, off-shore islands. Crotalus ruber is noteworthy for this as is C. molossus), basilisks (actually runs on the waters surface to escape predators, Jesus could take a lesson), armadillos, most members of the Weasle family, and the list goes on. All of these are far more efficent in the water than even Mark Spitz.

I cannot close off my nostrils, and I'm an ex-Navy diver. Guess I never learned the trick. Come to think of it, I've never met anyone who did learn the trick.

South Sea Islanders are no more aquatic than anybody else. Just better seamen. They fish from boats, use cast nets and dive for abalone, just like the rest of us.

I saw a documentary on PBS, a year or so ago. It showed crocodiles and hippos living together in a sort of uneasy truce. Apparently, this situation is fairly common.

I have yet to see any evidence worthy of more than a chuckle for our 5+ million-year-old ancestor to have been more than an opportunistic forager on the shores. As are we.

doov

Amen-Moses

I said land mammals! Polar bears are definitely semi aquatic (they have to be as they eat seals!), I'm not sure whether a Kodiak bear could outswim a human but they also live on an island and eat fish don't they? Weasels are good swimmers but not for long distances and I doubt if they will even cross wide rivers. How did weasels (and stoats and martins) become such good swimmers btw? Do you think their similarities in shape to Otters is purely coincidental?

I'm surprised you can't close your nostrils I've met very few people who couldn't do it to at least some extent and with a bit of practice it becomes easier, babies do it instinctively btw.

(the populations that can't tend to be Aboriginal Australians, West Africans (especially around Namibia) and North East Asians (Mongolia iow). I'm not sure about the Plains dwellers of North America or Inuits though).

Full grown and adolescent Hippos are not on the Croc's shopping list but come baby bearing time Hippos will actively drive away any Crocs (expecially large ones) in the area. It is probably more fair to say that Croc's will avoid Hippo families if they can and are wary of feeding near them.

As to south sea islanders they may go out with boats but they hunt in the water, i.e by diving for up to 3 minutes at a time and swimming down considerable depths, a strange thing for a forager to do don't you think?.

Amen-Moses

Duvenoy

Not at all. I've known a number of people who could do this, none of them Islanders. When spearfishing, I could easily stay a minute at depths to 60 feet or so, and I wasn't especally good at it. It's nothing but conditioning. And why should they not explore their enviornment and exploit what they find? The seas around these islands are very clear and one can see the bottom at considerable depths. Greek sponge fishermen and Italian coral divers also worked deep before the invention of diving gear. Also, Japanese pearl divers, before cultured pearls were being farmed. Deep, free-diving has been done by many cultures. Nothing new nor unique under the sun, eh?

Speed in the water means nothing, unless it involves a hungry predator. Efficency in the water is what's important, and we are anything but efficent.

Weasle's shapes are also ideal for their terrestial nitch, as many if not most, hunt and feed on land. They are almost as adept as a snake in moving through brush, rocks, and rubble in search of prey.

I can't decide whether to give you the polar bear or not. Only a small percentage of their time is actually spent in the water. Mostly, they roam the ice pack in the winter and come ashore in the warmer months. They hunt mainly by waiting at a seal's breathing hole in the ice. When the seal comes up for air, they snatch it out, or try to.

But, they are the most efficent swimmers among bears (and all bears are good swimmers).

doov

Amen-Moses

Originally posted by Duvenoy:
Not at all. I've known a number of people who could do this, none of them Islanders. When spearfishing, I could easily stay a minute at depths to 60 feet or so, and I wasn't especally good at it. It's nothing but conditioning.

Precisely, virtually all humans can do this with practice. I'm not sure whether even a Polar bear can do the same though, their main use of swimming (which nonetheless is extremely important to them) is in order to cross open expanses of water and as you point out they tend to wait for seals to surface before attacking them but they can hunt in water as well (not always for seals but for other food).

And why should they not explore their enviornment and exploit what they find? The seas around these islands are very clear and one can see the bottom at considerable depths. Greek sponge fishermen and Italian coral divers also worked deep before the invention of diving gear. Also, Japanese pearl divers, before cultured pearls were being farmed. Deep, free-diving has been done by many cultures. Nothing new nor unique under the sun, eh?

I think you are making my point for me.

Speed in the water means nothing, unless it involves a hungry predator. Efficency in the water is what's important, and we are anything but efficent.

So how can a human swim 21 miles in extremely cold and rough seas? How many other land mammals would be capable of such a thing? (Elephants and Polar bears again are the only ones I can think of?) In the warmer seas of the pacific ocean people swim even further than that, how efficient do you want us to be? Even Sea Otters would be hard pressed to swim that far without stopping to eat or sleep.

Weasle's shapes are also ideal for their terrestial nitch, as many if not most, hunt and feed on land. They are almost as adept as a snake in moving through brush, rocks, and rubble in search of prey.

True so did this shape evolve first on land and then find a niche in the sea (like the Otters) or is the Ferret/Stoat/Martin family from an ancestor that came back from the water (like Elephants and Hippos possibly are). I believe that stoats are especially adept at hunting water rats and voles which burrow along river banks and don't Beavers make their homes specifically to avoid such predators? Would you classify this as a semi-aquatic environment?

I can't decide whether to give you the polar bear or not. Only a small percentage of their time is actually spent in the water. Mostly, they roam the ice pack in the winter and come ashore in the warmer months. They hunt mainly by waiting at a seal's breathing hole in the ice. When the seal comes up for air, they snatch it out, or try to.

From videos I've seen they also pounce on seals whilst in the water and in one memorable video (memorable because of the extreme lengths the camerman went to get the footage) I've seen a Polar Bear hunting huge Cod under water, basically by taking a flying leap off an ice drift into the middle of the school and stunning the fish long enough to grab one.

But, they are the most efficent swimmers among bears (and all bears are good swimmers).

When you regulary wake up on an ice drift tens of miles off shore it is a damn useful trait to be able to swim long distances. Did you know that unlike other bears the male Polar Bear does not make a den for winter but instead just lies down and hibernates wherever he happens to be. Because they have no natural predators they don't have to hide. On land bears like the Black Bear and to a lesser extent the Grizzly have to hide away from the likes of Wolves and (in the past at least) large cats whilst hibernating. Seeing as how Polar Bears cannot predict which bit of ice will melt first they are taking pot luch that they won't wake up on an iceberg in the middle of the Atlantic. (although they probably wake up well before they have left the artic circle)

As to all bears being good swimmers I have no doubt that Black, Brown etc bears are but what about the Honey bear or Panda? Could the fact that the first group live in areas where spring melts provide ample flooding whereas the second live in pretty stable forest/jungle environments explain any difference in ability?

One other video snippet I can recall which was extraordinary (from the same extremely brave camerman IIRC) was that of a Polar Bear stealing a kill from a Killer Whale! The Whale came up to breath where Polar Bear was waiting to pounce and happened to have caught a seal (which was also probably coming up to breath) the Polar bear quickly snatched the seal in its jaws and sort of kicked at the nose of the whale but fell into the water whilst doing so. The cameraman just kept filming but thought that the Polar Bear was probably a goner then a few minutes later the Bear came back up through the hole still with the seal in its jaws and then wandered off to eat it, they are indeed fearless creatures. (it is possible that Killer Whales don't attack Polar Bears of course but you have to wonder how the Bear knew that!

Amen-Moses