@Alan McDougall,
Alan McDougall;105549 wrote:THE FEMALE PELVIS Human adaptation to walking upright has made giving birth more dangerous for women than for any other primate.
Sure. Now if you believe in intelligent design or creationism - why did God make it like this?
Evolution favours the following explanation:
Bipedalism saves a lot of energy.
It also frees up our hands for tool use, which is a major reason for our success.
It has the disadvantage that birth is difficult and that back problems plague humans in later life.
However, the energy saved and the boons provided by tool use make us more successful in our given niche than quadrapeds.
The advantages outweigh the disadvantages, so bipedalism stays dispite it's problems. Over time human tool mastery, as well as a slight widening of hips, have made birth much safer for women.
Quote:LINEAR CHROMOSOMES The ends of linear chromosomes erode as cells divide, something that
cannot happen with circular chromosomes
I'm not sure why this is a challenge.
Quote:EXTERNAL TESTICLES In harm's way VAGINA AND URETHRA NEAR ANUS Leaves women
prone to genital and urinary infections
Sure - nasty. Now if you believe in intelligent design or creationism - why did God make it like this?
Evolution first developed sperm and testes in fish. Sperm works best at a relatively low temperature - no problem for fish as they live in an effective coolant - water. Amphibians live in water most of the time too. Reptiles have cold blood, so just need to get out of the sun if they are overheating.
Mammals have warm blood, and if the testes were kept in the body cavity sperm would lose motility.
So an adaptation has occurred whereby the testes develop in the chest (like fish) but travel down to the scrotum. Most of this happens before you are born, but the final stage occurs in puberty (the dropping of the testicles).
Whilst the scrotum is vulnerable, it is cooler than the rest of the body, meaning that more sperm benefit from the lower temperature, and making it more likely that a mammal with the adaptation will father children han one without.
Quote:WISDOM TEETH Many of us have jaws that are too small for these third molars
Yeah, ouch, I needed some of mine removed to avoid an infection that would have eventually killed me. Thanks modern science of dentistry!
Now if you believe in intelligent design or creationism - why did God make it like this?
Biologists generally propose to explain it thus.
Early homnids such as Australopithicus aferensis and Homo habilis began to develop a vocabulary of language and facial expression that is much more varied and intricate than other great apes with longer muzzles.
The benefits of being able to better articulate facial and vocal expression outweighed the disadvantage of increased problems with rear molars.
Quote:MUTANT GLO GENE Like most primates, humans cannot make vitamin C, rendering us vulnerable to scurvy unless we get plenty in our diet
Now if you believe in intelligent design or creationism - why did God make it like this?
Biologists think our original niche was pretty rich in fruit - hence no need to get vitamin C from other sources.
Scurvy only becomes a major issue when humans place themselves in an environment with no readily accessable vitamin C - such as a long sea voyage.
However, our mastery of tool use has overcome this problem - we now can carry pills of vitamin C into space.
Quote:THE APPENDIX No known function but if it gets infected it can kill you
Yeah, ouch, I needed mine removed to avoid an infection that would have eventually killed me. Thanks modern science of surgery!
Now if you believe in intelligent design or creationism - why did God make it like this?
Biologists think it's a vestigal organ that helped our ancestors digest uncooked complex starches, proteins and fibre, and the like.
Thanks to our mastery of tool use we now cook our food and don't require our appendix (though some research shows that it helps pregnant women in an as yet unexplained manner).
The appendix is still there (it doesn't just go away because we don't use it) but because it is no longer needed for our survival it has become vestigal - like the eyes of an animal that lives in a cave.
Vestigal organs can still get infections, and the appendix is notorious for such because it can provide a handy home for bacteria.
Quote:WINDPIPE NEXT TO THE GULLET Means choking is not uncommon
Now if you believe in intelligent design or creationism - why did God make it like this?
Biologists point out that it's not a problem for fish. They breathe over their gills so a blocked gullet doesn't starve them of air.
They might eventually starve to death - but they'll have plenty of time to try and get their gullet unblocked.
When animals developed lungs, and made the move to land - it bacame an issue.
But the benefis of terrestial living outweigh the disadvantage of occasional choking - so the gullet/windpipe stays because evolving an extra orifice unfortunately did not occur.
Quote:ULNAR NERVE Runs behind the elbow, where it is unprotected (think funny bone), instead of in front of it
God made it so why?
As prior example - it does in us, but it doesn't in animals biologists reckon we evolved from.
Quote:VULNERABLE BRAIN CELLS A few minutes of oxygen deprivation causes permanent brain damage in humans, yet an epaulette shark can survive for over an hour without oxygen
Sure, but the metabolism of a shark is designed to cope with a niche that is cool, under pressure and very different to ours.
Quote:PARASITIC DNA Our genome is littered with "jumping genes" that can cause genetic diseases
Yes, to our perspective, but these genes are also subject to natural selection, and trying to find a way to (unconsciously) survive and replicate. Some of them are - unfortunately - good at it.
Quote:ODONTOID PROCESS This extension of the last neck vertebra can easily fracture and damage the brainstem
But the benefits of balancing our head atop our neck outweigh this disadvantage.
Quote:FEET After coming down from the trees, we ended up walking on the "wrists" of our lower limbs, leading to all sorts of structural weaknesses
Again, would you rather be subject to twisted ankles, or live in a tree?
Benefits > disadvantages.
Quote:THE Y CHROMOSOME It is gathering mutations because it can't swap DNA with the X chromosome
But why is this an objection?
Quote:VULNERABLE HEARTS A little heart damage triggers a disastrous cascade of events that causes further damage
Most complex organs suffer similar issues.
But you're better off with a complex heart that might go wrong than a simple one that wouldn't support a terrestial mammal of some size.
Now if you believe in intelligent design or creationism - why did God make it like this?
Quote:HAIRY BOTTOMS Who needs them?
Many animals without clothes to help regulate temperature. We use clothes, so our body hair is vestigal, and we tend to associate it with "animalness".
---------- Post added 11-24-2009 at 07:55 AM ----------
jeeprs;105555 wrote:Consider this: if it is true that 'nature is dumb' and all of life has come about through 'unintentional causes' then ipso facto the only purposes in nature are those which conscious beings - that is, ourselves - are capable of forming.
Sure - it's my understanding that this is what Existentialism's all about.
Or absurdism, if not.
Quote:In saying this, I am saying nothing that Plato, Liebniz, Descartes, Spinoza, Kant or Hegel would say.
But would they have said it if they were cognizant of modern understanding of the theory of evolution?
---------- Post added 11-24-2009 at 07:58 AM ----------
Alan McDougall;105566 wrote:It is incomplete in one absolutely important fact, evolution does not explain how life started, how it morphed from inanimate elements into living protoplasm
Evolution never laid claim on this.
It's hypothesised through Abiogenesis.
I posted two videos about it in answer to one of your earlier questions.
Did you watch them?
Protoplasm - by the by - is a pretty arcane term. It's a Victorian idea about cellualr life which has since been overturned.