bombus

To bombus

 

Humans are lousy swimmers, unless trained and experienced. The fact that babies can survive for a brief time in water can be explained by evolutionary processes apart from actually being aquatic. Survival from drowning for long enough for a parent to rescue them is something else. After a relatively short time without rescue, even that capability is not enough, and the baby will die. The baby cannot swim to shore, which seems to me to be a very basic and essential skill for even a semi-aquatic mammal.

Lets face it, humans are pretty lousy at everything until trained and experienced, but the ability of human babies is NOT that easily explained. Nor would the ability to survive from drowning for a short period be something a terrestrial mammal would evolve. IMHO it points to humans giving birth in water - probably as a protection from predators. It gives the mother enough time to gather it in its arms.

Drop a new born puppy, or even chimp into water and see what happens!

The ability to swim as adults is widespread among fully terrestrial animals. Even elephants are much better swimmers than untrained humans as adults

They can't hold their breath as well though!

And the adult human ability to breath hold dive is not natural. I know. I am a keen scuba diver and snorkeller. That ability is one obtained by training and practise - something other terrestrial animals do not do. And the vast majority of people, despite training, cannot come within an order of magnitude of what a seal can do. Only a tiny percentage of human divers can develop to the point of even spending two minutes swimming underwater while breath holding. Personally, even after many years of snorkel diving, my comfortable limit is less than a minute. A seal would laugh at me!

Oddly much of the ability to hold breath underwater is actually psychological. Free divers can overcome the natural desire to breath and stay submerged for much longer than most of us could. The point is that humans have a physiological ability to do this far in excess of what we should be expected to have.

There is a chance that pre-humans may have been waders, but not very aquatic apart from that. Untrained humans are actually lousy swimmers, so we are definitely not pre-adapted by evolution to a fully aquatic life style. It is also clear that our ancestors have not spent much time in salt water, because there are no fossils found in salt water deposits.

Human babies can swim as soon as they are born. They automatically hold their breath, rise to the surface and do not breath until their face is out of the water. They retain this ability until around 3 months old. Humans are actually far better swimmers than they deserve to be, and our ability to hold our breath underwater far surpasses any terrestrial mammal. In fact it is almost on par with seals. We would not have been fully aquatic at any time, it's a bit of a misnomer, but semi-aquatic. maybe living on and foraging in coastal areas. I doubt fossils would be found in the way you suggest. they would probably be found in what were coastal areas (and possibly are?).

If our ancestors were sea water hunters, many would have died in the sea and been partly or wholly buried in sea sediment, and fossilised as such. After all, sea sediment is one of the very best ways of making fossils.If you look at the fossils that exist of pre-humans, they are not marine fossils. Thus, pre-humans spent little time in the sea.

As the answer above, I doubt we'd have been sea hunters, but maybe we lived off seafood (shellfish etc). In fact, a seafood diet is the healthiest for humans as its full of omega 3 and oils that keep our arteries clear.

CD Dawin,

I have seen that anti AH website before. It is full of strawman arguments, and inaccuracies. Your point about most aquatic mammals being 'haired' is interesting, but not actually that important. Most aquatic mammals have short or no legs but frogs have long legs - it all depends on what the starting point is and what evolutionary processes then come into play. Maybe we were living in muddy waters or boggy areas where hair was a disadvantage. Also cetaceans have no hair, as do hippos, elephants, rhino's, all of which are either semi aquatic or have had semi aquatic ancestors.

Quite a substantial difference. Putting weight on the front limbs predisposes an entirely different posture than putting weight on the hind limbs. You can think of it two ways, in terms of balance and in terms of a gradation between a hand-stand and walking upright. In a hand-stand all the weight is on the front limbs, in a baboon the majority of it is, in an ape a minority of it is, and in an upright human none of it is. Also think about trying to balance yourself standing upright if most of you weight bearing muscles were in your upper body. It would be impossible. In apes the weight-bearing muscles are already in the lower body, as they are in humans.

 

This entire argument is built on conjecture. Gorillas put huge weight onto their front limbs when walking, and so do chimps.

 

 

 

 

 

 

 

Not much difference between the two. The female proboscis nose isn't any more significant that male nipples. It's not that important what the proboscis nose is used for though, since the human nose projects as it does as a simple consequence of the foreshortening of the face. When you bring an ape's jaw in, there's nowhere for the nose to go but to jut out.

 

Well, it could be that it was an evolutionary advantage for swimming and so became an attractive feature that went into 'overdrive' in the males - like the peacocks tail. However, it's not a particularly important factor in the argument.

 

 

Holding your neck up doesn't count as bipedality, nor does the standing upright for short periods that otters might do when many other terrestrial weasels (think meercats) do it much better.

Ever seen a sealion hold a ball on it's nose? Meercats couldn't do that. I'd bet otters have much better balance than meerkats too.

 

 

 

Our feet aren't flipper shaped in any meaningful way. What they are is perfectly designed (down to the position of the toes) to give a surface to launch the body forward with each stride. The only thing our feet show any especial adaptation to is good, bipedal locomotion. On land. And the early australopithecine feet that have been found don't look like flippers either. They look like ape feet that have been jerry-rigged for efficient, bipedal locomotion. Any encounters with water during this evolution was by all appearances irrelevant to this trasformation. We never needed a stage where our bodies were preadapted by an aquatic lifestyle, the ape foot itself had enough plasticity to serve as the beginnings of a fine biped extremity.

 

Well I'd say they are pretty flipper shaped compared to other primates. Your note about the feet of australopithecines is interesting. It's possible that it was about this time that they homonids became semi-aquatic.

 

Promising to explain lots and lots of things and then offering piteous support is no virtue of a scientific theory. It may sell books, but that's about all.

 

It's simply not true that there is piteous support. There is loads. Even Sir David Attenborough is a recent convert to the theory.

It means generating massive profits for the oil companies. Nothing to do with the people at all. Those corporations are more than willing to sell to the highest bidder, whether that bidder is the US, China, or Gilligan's Island.

Absolutely right! Not only that, but the 'defense' industries have made £billions out of Iraq. That's why they are happy to have a war with Iran - or anybody else for that matter. The poor soldiers pay with their lives to keep the bosses rich - as ever...

No. What is amazing how some cling to outdated and falsified hypotheses, all the while ignoring or twisting evidence. Hostility? At times. Too many religious nuts and too many mixed nuts makes that happen. More often, the response is more along the lines of

Outdated, falsified hypotheses? That well describes the savannah theory. A Victorian theory, way out of date and contrary to the evidence.

I am right I tell ya. Just you wait and see!!!

Apes don't walk like baboons, though. Baboons stride much like cats or dogs, putting a preponderance of their weight on the front limbs. Apes put most of their weight on their hind limbs and live a surprising amount of their time upright in trees. And it's amongst the trees that bipedalism probably evolved.

There is hardly any difference between them.. I feel you are clutching at straws!

Male proboscis monkeys have an pendulous nose, probably as a result of sexual selection. If this is an adaptation for swimming, females seemed to have missed the boat. Or rather not missed the boat, I suppose. I've never seen anything about them regularly walking upright. They have a fairly upright posture in the trees, but so do all colobine monkeys. It would seem much more likely that being upright was a preadaptation for swimming, rather than swimming was a preadaptation for being upright. I'm also not sure what structure of the human nose you're referring too.

The females still have longer noses than most monkeys. The human nose flap I refer to is, well, the human nose. C/f other primates noses! I may be clutching at straws here...

I get that all of them have hind-limbs that point more-or-less back away from the body (otters not so much). But the point is that even though they have this body arrangement, they all still walk quadrupedally on land. We're not swimming around typing on this message board, we're on land. So if aquatic ape is going to be able to refer to the body arrangements of truly aquatic animals as evidence, those arrangements are going to have to translate into a locomotion vaguely human-like while on land. Instead, we have seals that flop, otters that run like the weasels they are, cetaceans that just die, and penguins that waddle inefficiently (even if they are 'upright').

Penguins don't walk quadrupally on land. The others have no choice, but the balance and ability to stand kinda upright shown by sealions, and otters for that matter, are abilities that an aquatic or semi-aquatic lifestyle can bring. Homonids had long legs to start with though, so these would have been used in a fashion similar to frogs, which are also swimmers with long legs. So, our body form would become elongated and 'straight' effectively pre-adapting us for walking upright. Also look at our feet - they are flipper shaped.

You (or someone, rather) will have to find some actual fossil or archaeological evidence. And then you would refer to it, and I would feel very sheepish and bemused. But not today! Which I can say with confidence since you probably won't post again today.

Fossil evidence is already there - it just depends on the interpretation. It's amazing how hostile people are to the aquatic theory despite it answering ALL the questions about human evolution (hair loss, sub cutaneous fat, babies swimming as soon as they are born, tears, dive reflex etc etc etc) - unlike the savannah theory.

It is the truth, and I will one day be proven right, and everyone will pretend they agreed with me all the while...

Early humans didn't live on the savanna, they lived on the forest edge, and they didn't evolve from baboons who are highly specialized to move on all fours on the ground as efficiently as they do and evolved from ancestors who also moved on all fours. Humans evolved from apes, which, as you point out, already have a propensity for upright movement.

I know humans didn't evolve from baboons, but they did evolve from the common ancestor of humans and chimps. I'd bet they were very chimp-like and walked on four limbs most of the time. Why would they walk on two legs when they moved out to the savannah if four legs is better and evolution could have taken them either way?

You want to look at modern savanna dwelling primates to demonstrate that savanna adapted primates are always quadrupedal. Well, look at water-adapted primates. Talapoin monkeys (Miopithecus talapoin), Allen's swamp monkey (Allenopithecus nigroviridis), macaques, and proboscis monkeys (Nasalis larvatus) all swim frequently. All are quadrupeds or partial brachiators and all show adaptations like webbed feet missing in humans.

Proboscis monkeys are thye best swimmers, and regularly walk upright. They have also developed a nose flap that prevents water going straight up the nostrils - like humans maybe?

Of the animals you listed, only penguins actually walk upright on land. I'm really not sure where you got seals from. And penguins walk upright principally because they're birds. Have you ever seen a quadrupedal bird?

I know that only penguins actually walk upright, but the others all have a body aligned in a similar way, it's just that they don't walk upright as they can't! Maybe you miss the point?

Penguins btw are the only truly upright animal apart from humans. Other birds are not truly upright.

I accept your point, but there is a difference in opportunity.

 

Those that stand all of the time still can duck so as not to be seen.

However, those that are on all fours most of the time are still more frequently surprised by attack from (and eaten by) predators.

 

Over time, those that were more upright more of the time had a selective advantage.

 

 

I'm speculating here. Let me make that clear. If I'm wrong, I'm okay with that, but I'd like to know why.

Meerkats stand upright to look out for predators, but still run on all fours.

It's swimming that did it. One day I'll be proven right...

Swimming.

Without a doubt IMHO.

Savanahh living primates are more likely to run on all fours compared to forest dwellers (c/f baboons v orangutans)

C/f penguins, seals, sea lions, otters, cetaceans, all have a fully 'upright' stance (seals, cetaceans etc lie flat, but the body design is similar)

thanks for your answers everyone

If cosmic rays are so powerful (and I'm sure they are), why do we need to build the LHC at all? Can we not just study particles that get hit by cosmic rays? They are so numerous afterall.

Is the fact that the LHC slams particles together head-on at near light speed the difference? If so, does that not make the cosmic ray comparison a little shaky?

Please someone explain in very simple terms.

What is a "subspecies" versus a "breed"?

 

A Wildcat (Felis silvestris), has five subspecies, but a house cat (Felis catus) doesn't have subspecies, but breeds.

 

For example, a siamese and a maine coon are very different in appearance and behavior, so why shouldn't they be considered subspecies?

 

Thanks for any help.

The criteria for species and sub-species are not particularly strict and are open to interpretation. It tends to boil down to convenience if the truth be told. Some class Felis domesticus/catus as a sub-species of F. sylvestris, others don't.

Also, it would seem some divide F. catus into subspecies:

* F. catus anura - the Manx

* F. catus siamensis - the Siamese

* F. catus cartusenensis - the Chartreux

* F. catus angorensis - the Turkish Angora

could this not have waited until we could do it in space though, just to be on the safe side?

yes, there is a big difference between "can't interbreed" and "don't interbreed". Only the latter is meaningful in nature.

Well, that's not quite true. Species that can interbreed but don't (e.g via geographical isolation, or behaviour) tend to diverge intospecies tat cannot interbreed. The latter is usually a forerunner to the former.

1 - All insects are winged (unless they secondarily lost their wings).

This depends on your definition of an insect. Silverfish for example are classed as Class Insecta in many texts.

I think the term Hexapod/Hexapoda is now used instead of Insect/Insecta to include all six legged arthropods including both Apteregotes (all wingless insects) and Pteregotes (winged and secondarily wingless insects).

It appears to be complicated. Some people are hypothesizing that crustaceans and hexopods (of which insects are a part) form a clade called "pancrustacea".

 

A news summary in Science is here: http://www.sciencemag.org/cgi/content/full/314/5807/1883

 

http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1634985

 

The most recent comprehensive book about insects and their evolution is here: http://www.cambridge.org/uk/catalogue/catalogue.asp?isbn=0521821495

Interesting stuff. I like cladistics!

I am relatively new to the Forum so take it easy.

 

However, despite the life cycle of bacteria (20 minutes per cell division in rich medium), bacteria have stayed bacteria over millions of years. They also would have more mutation due to the sheer rate of cell division than animals so why have they stayed bacteria? Also the same with flies.

Some bacteria have stayed bacteria, others have become extinct, and some of those have evolved into more complex forms of life.

Currently exisiting species of bacteria do very well as they are, have little need to 'evolve' and will undoubtedly outlive humans and possibly everything else too. Being complex does not make one any better. Evolution only cares about which genes get passed on, so if the best way to get ones genes passed on is to stay as one is then there is no selective pressure to change - and quite the opposite in many cases.

Some may be interested in the excerpt below from a paper by Nick Bostrom:

There have been speculations that future high-energy particle accelerator experiments may cause a breakdown of a metastable vacuum state that our part of the cosmos might be in, converting it into a “true” vacuum of lower energy density [45]. This would result in an expanding bubble of total destruction that would sweep through the galaxy and beyond at the speed of light, tearing all matter apart as it proceeds.

Another conceivability is that accelerator experiments might produce negatively charged stable “strangelets” (a hypothetical form of nuclear matter) or create a mini black hole that would sink to the center of the Earth and start accreting the rest of the planet [46].

These outcomes seem to be impossible given our best current physical theories. But the reason we do the experiments is precisely that we don’t really know what will happen. A more reassuring argument is that the energy densities attained in present day accelerators are far lower than those that occur naturally in collisions between cosmic rays [46,47]. It’s possible, however, that factors other than energy density are relevant for these hypothetical processes, and that those factors will be brought together in novel ways in future experiments.

The main reason for concern in the “physics disasters” category is the meta-level observation that discoveries of all sorts of weird physical phenomena are made all the time, so even if right now all the particular physics disasters we have conceived of were absurdly improbable or impossible, there could be other more realistic failure-modes waiting to be uncovered.

Sexual selection vs natural selection

 

We could get bogged down here in semantics. I could see valid arguments for separating the two, and other valid arguments for combining the two. Why don't we simply accept the scientific convention, and just regard them as two kinds, in spite of the valid arguments to the contrary?

It's not semantics, it's just that sexual selection IS one facet of natural selection. Others are competion (intra and inter species), environmental factors, behaviour, the list goes on. There is no need to separate out sexual selection, and it's often not easy to that anyway. Natural selection doesn't care about the reason - only if the individuals genes are successfully passed on.

Sexual selection isn't natural selection. Two different things. Darwin separated the two. Sexual selection falls under "nonrandom mating" in ways to disrupt a Hardy-Weinberg equilibrium. Natural selection is a different way to disrupt the equilibrium.

I would tend to disagree with that most strongly. Sexual selection is definitiely natural selection. It's not man-made selection so it is natural selection!

Natural selection does not just include competiton for scarce resources. Sexual selection produced the peacocks tail, and the plumage of many birds, and badgers stripes, and probably human's big brains.

That's the point, though. Top-down control cannot survive if the populace has a cheap means of bringing their government under control. Consider, for example, the Cromwell revolution in England, and the American revolution. Neither of these revolutions would have been possible without cheap range weapons (flintlock muskets).

Top down control can survive if those at the top own the means of production in a manner seen as being fair (even if it is not) and more importantly, if they control information!

Actually, the whole "interbreeding" thing is much more murky than one might suppose.

 

Yesterday I heard how two different species of frog interbred.

 

I though that 'species' are a definition of what can't interbreed?

There is no single definition of a species. It's a pretty fuzzy concept really.

Could the hybrid frog reproduce or was it sterile?

What is the exact date and time (in GMT or BST) that the LHC is to be run for the first time?

yeah, everybody lives longer, but not everyone reproduces. there are other forms of selection than simply survival of the fittest, there is sexual selection as well.

 

it is a common misconception that the only thing about evolution is natural selection.

Sexual selection is a form of natural selection.

Measures to prevent global warming could lead to increased prosperity due to employment in new sustainable technologies. Think (for example) how many people could be employed in the windfarm/solar/tidal/geothermal/biomass/nuclear industries, and how much shares in those technologies would be worth, and how much business that leads to, etc etc etc.

If the LHC at CERN does create mini black hole(s) and in the race between hawking radiation and matter munching the latter wins... How long would it take for the Earth to be destroyed?

If the LHC at CERN does create mini black hole(s) and in the race between hawking radiation and matter munching the latter wins... How long would it take for the Earth to be destroyed?