Yup, the video makes a good point.

Discuss. 🙂

a)It is mentioned in this website that humans evolved hairlessness to reduce parasite loads, especially ectoparasites that may carry disease. This might seem to be true at a glance. However, this could not be true on our heads since the hair on our heads could keep on growing and this would lead to ultimate parasite loads if it were uncut for more than 30 years. The total mass of the hair that a person would keep for 30 years would be a number of times heavier than the hair that has grown up in apesâ?? body. The only thing that causes human beings to differ from apes is the hair among the apes has been distributed over their bodies and yet human beingsâ?? hair is concentrated on their heads. When we compare the hair from human beings and apes, human beings could be parasite loads, whether in length or in mass, when the hair was uncut for more than 30 years. Thus, the hair among human beings could not reduce parasite loads. Instead, it might turn up to be the other way round to increase parasite loads on the condition that human beings did not cut their hair for more than 30 years. Thus, the hair loss among human beings and to cause it to grow continuously over the head might increase parasite loads and causes a disadvantage to human beings if their hair were uncut for more than 30 years. The over-concentration of hair growth on heads would not show any advantage in the long run since it would increase parasite loads.

b)It is mentioned in the website address above that hairlessness is made possible in humans owing to their unique abilities to regulate their environment via fire, shelter and clothing. Refer to the website address, http://en.wikipedia.org/wiki/Androgenic_hair, it shows the distribution of hair among men and women. Despite human beings might put on clothing, yet the hair among human bodies especially those parts that are covered by clothing would not reduce. This gives the implication that our hair might not be able to reduce in spite of our capabilities to regulate environment via fire, shelter and clothing. Or else, men and women should not have hair on those parts that have been covered by clothing.

c)It is also mentioned in this website that hairlessness, then, demands some sort of explanation in evolutionary terms, and especially so as, in humans at least, hairlessness is not without its costs. Humans are more exposed to the sun, may suffer greater heat loss when the ambient temperature is low (Newman 1970; Amaral 1996) and, with the exception of the naked molerats, differ from the other hairless mammals in not having a thick or toughened hide for protection.

d)Many people in this world might have encountered hair loss problem that leads to the ultimate bald heads to annoy them and causes them to have no choice but to seek help from clinic, hair salon and etc. Yet this hair loss problem persists from generation to generation. As hair loss could cause problem among human beings and yet it persists, it places the query about the reliability of evolution. This is due to why there should be hair loss that would result in bald heads among human beings and this could not occur among apes or other animals.

e)Human beingsâ?? hair loss brings about the disadvantage of causing them to turn up to be gray or white at old age and this might be in concern by the old folks. Yet the situation could not change unless dye hair. However, this disadvantage of turning into gray or white hair could not occur among other animals especially apes. Or in other words, there is a disadvantage of hair loss among human beings as a result of gray or white hair in old age and this places the reliability of evolution into question.

f) It is mentioned in this website that Wheeler (1992) acknowledges that naked skin increases the rates of both energy gain and loss during periods of too much or too little heat, respectively. This might mean that naked skin is actually a worse solution when the entire day is taken into account: more heat must be dissipated from daytime exposure and, at night time, more heat is lost (Amaral 1996). 3. There is certainly a disadvantage of hair loss here due to rapid energy gain and loss as a result of hairless condition of our bodies.

Despite of our hair loss, the redundancy of hair in length, such as underneath the armpit and even from the front body onwards up to the legs, remains there without removing away or evolve away, brings a query about the reliability of evolution since what it tends not to be used and yet it still retains instead of vanishing away.

It is also mentioned in the website that humans are not literally hairless, having about the density of hair follicles expected of an ape of our body size (Schwartz & Rosenblum 1981). What distinguishes human body hair is that it is very fine and short, making it, effectively, invisible. we use â??hairlessâ?? with respect to humans, then, to mean that they lack a dense layer of thick fur. However, this could not be true to the hair that is on our heads that could grow exceedingly and could even cause parasite loads on our head if this has been uncut for 30 or more years. Indeed, the hair on the human beingsâ?? heads is the longest among all animals.

It is also mentioned in this website that hair loss could be meant to promote cooling of the body. However, many men might have exposed half nakedness of their upper bodies and yet could not feel cool on their bodies and seek help from fans or air-conditioning system or breeze or etc. even at the absence of sun especially early in the morning or at night. Some people might even suffer from high fever and need to seek help from doctor despite hairless bodies could cool it down. All these have placed the query whether hairless bodies could really cause their bodies to be in cool.

From the above analyses, there places a query why there should be hair drop and it seems to have adverse effect of evolution and that places the reliability of evolution into question

I like this “carving nature at its joints” metaphor.

I didn’t originate it, I hasten to say! Apparently Plato did–he puts it in Socrates’ mouth, but that usually means he just made it up–in the Phaedrus.

I am, however, not overly happy with what most people are actually thinking when they think any one of the four terms the post started with.

Oh, yes. Most people are either thinking “My grandfather wasn’t no chimpanzee!” or “My grandfather was a chimpanzee, I saw it in a movie!”, neither of which is particularly helpful.

Just one mostly off topic thing to add. As far as I’m aware, gibbons and siamangs are fully bipedal and spend a surprising amount of time on two feet, although they don’t run in a fully upright position or extend the leg at the knee like humans do. When moving quickly through the canopy, they seamlessly switch between swinging leaps and quick sprints along larger, mostly horizontal branches. The internet is letting me down right now, in that I can’t find a single example of this, but I have found something close with this video of some little prick harassing a dog.
http://www.youtube.com/watch?v=DoQwOVAN2kk&feature=related
Which is Better: Apes or Dogs?

Yes, “dinosaur” is a scientific term, but one originally used to describe a morphologically-similar set of extinct animals known only from their fossilized remains. Despite the clear line of descent, it’s simply wrong to say that birds belong in this group — they actually have few common features, having quite moved on.

This seems flatly wrong to me. Birds share a host of common features with dinosaurs, as they do with archosaurs, as they do with reptiles in general. Skeletal anatomy, scales, feathers, egg-laying patterns, even behaviors like nesting and parental care and gastrolith use and vocal communication. “A theropod dinosaur specialized for flight” is a near-perfect definition of a bird.

Now, do birds have much in common with dinosaurs as they were originally characterized? Nope. But the people who originally characterized dinosaurs didn’t know very much about them. I mean, if we were still defining dinosaurs around the features Owen thought they had, we’d have to say that dinosaurs are entirely mythical–because his semi-mammalian, obligately quadrupedal, massive-forelegged reconstructions don’t resemble any dinosaur that ever actually existed.

“Dinosaur,” like any scientific label, is an attempt to carve nature at its joints. If the joints turn out not to be exactly where we thought they were, there’s absolutely nothing wrong with updating the definition to match. The evolution of the term “dinosaur” from the 19th to the 21st century reflects genuine progress in our understanding of the critters. In my non-expert opinion, anyway.

Birds are universally small while dinosaurs, especially in the original conception of the term, are generally large (this is why, in fact, they are called dinosaurs — the name was meant to evoke, as it does to this day, saurian creatures of tremendous size and power)

But “generally large” and “universally small” (where “small” includes, I assume, “ostrich-sized”) are not incompatible. Mammals are generally small (most species being bats, rodents or insectivores) and elephants are universally large, but that doesn’t mean elephants aren’t mammals. They’re just big mammals.

Yes, dinosaurs include creatures of tremendous size and power, but–in the age of Jurassic Park and The Land Before Time–even laypeople are comfortable with the notion that they’re not all like that. Even if you leave out all the not-quite-birds like Archaeopteryx and Microraptor, there are well-known card-carrying dinosaurs like Compsognathus and Velociraptor that fall well within the size range of modern birds. And Velociraptor’s feathered and (moderately) warm-blooded to boot.

Birds (with some exceptions) fly, other dinosaurs (without exception) do not. Dinosaurs generally have teeth and large, flexible tails. Birds do not.

Well, “without exception” only if you define all the dinosaurs with powered flight as birdsâ?¦.in which case, it’s no longer true that birds don’t have teeth or large, flexible tails.

More importantly, even a truly unique feature of one group doesn’t preclude it from being included in a larger group. Bats fly–without exception, at least among modern species. Other mammals, without exception, do not. That doesn’t mean that bats aren’t mammals, it just means that bats are flying mammals, and that flight isn’t a good criterion for classifying creatures as “mammal” or “non-mammal” in the first place.

Set an unfamiliar (nonbird) dinosaur side by side with an unfamiliar bird, and I will wager I can tell the difference without even inspecting them closely, whether they are presented only in skeleton (though I will have to insist on a full skeleton — I’m no paleontologist) form or in life with full scales and feathers.

Forgive my skepticism, but many paleontologists have spent years wrangling over whether this or that maniraptoran dinosaur is a bird or a non-bird. I honestly don’t think you could tell the difference in many of those cases…no one can. (Which is not at all surprising from an evolutionary viewpoint, of course.)

Reptiles (by definition) are cold-blooded and scaly.â?¨Mammals (by definition) are warm-blooded and hairy.

And yet Mammals are phylogenically Reptiles, and thus we reach a contradiction. It is impossible to define the terms “Reptile” and “Mammal” so that they are both morphologically consistent and cladistically valid.

That doesn’t actually follow. If you define them cladistically, they’re still morphologically consistent–it’s not like Reptilia/Sauropsida doesn’t have any synapomorphies! You just can’t use “cold-blooded vs. warm-blooded” as the morphological distinction. Not that you could anyway, if you wanted all dinosaurs to be reptiles.

Worse, we’ve been telling kids for a great many years that cetaceans are not fish, and yet it is impossible to construct a cladistically-proper class that includes all fish and yet excludes whales (or humans, for that matter.) Are humans fish?

Oh yes, “fish” is totally cladistically unsalvageable. A monophyletic “fish” would either have to include bears and parrots and toads and iguanas, or exclude sharks and lampreys and stingrays and coelacanths and lungfish, both of which options take you way, way outside any normal meaning of the word. But that’s quite a bit worse than just having to throw birds into “dinosaur” or “reptile,” IMO.