Natural Selection- is the human species really the ultimate design?

So I've been thinking about the human body in terms of evolution and natural selection...

I believe in evolution to some degree - and some would say I've got my own distorted ideas about evolution and natural selection/survival of the strongest.

So this sums up Natural selection (according to Darwin), right?



Or in short Natural Selection is the differential reproduction of genotypes.

BUT for natural selection to occur, two requirements are essential:
There must be heritable variation for some trait. Examples: beak size, color pattern, thickness of skin, fleetness.
There must be differential survival and reproduction associated with the possession of that trait.
Unless both these requirements are met, adaptation by natural selection cannot occur.

For example:
If some individuals are fleeter than others because of differences in their genes, but the predator is so much faster that it does not matter, then no evolution will occur (e.g. if cheetahs ate snails).

In addition, natural selection can only choose among existing varieties in a population. It might be very useful for polar bears to have white noses, and then they wouldn't have to cover their noses with their paws when they stalk their prey. The panda could have a much nicer thumb than the clumsy device that it does have.

When we incorporate genetics into our story, it becomes more obvious why the generation of new variations is a chance process. Variants do not arise because they are needed. They arise by random processes governed by the laws of genetics. For today, the central point is the chance occurrence of variation, some of which is adaptive, and the weeding out by natural selection of the best-adapted varieties.

So, the question is, is the human body really the "perfect design" to survive and to be the top of the food chain?

Don't get me wrong; the human body is really an extra-ordinary design with some amazing features. But there's so many "flaws".
For example why do we only have one set of teeth? Why not grow a new tooth when you loose a tooth like sharks? Back in the cavemen days they probably had bad hygiene - so by 60 they probably had little teeth left meaning you could only eat soft food.
And while we're growing new stuff, why not the ability to grow a new limb like a lizard grows a new tail? If we came from the same gene pool - millions of years ago - then we should have had genes like that? If you lost a limb back in "the old days", your chances of survival became even smaller.

The human body is extremely fragile, and our only defence against predators is brawn. Is that it? Was our ability to adapt and think creatively the only thing that saved the human species? If we grew poisonous tails like a scorpion to survive would this mean that we wouldn't have been so "smart"? And why are we so susceptible to diseases? Our immune system is quite weak compared to other animals - like dogs, crocodiles, roaches, etc. How did we survive this long? The planet wouldn't have been this densely populated if it wasn't for modern medicine. Look at HIV/AIDS. Look at how it's wiping out our species just because we can't find a cure. Back in "the old days" they didn't have any cures for illnesses like leprosy, pocks, etc. It's an endless list. BUT we survived all of that somehow. Why wasn't that survival mechanism kept in our immune system?

And when we "mutate"/evolve, we evolve the "stupid ability" to digest milk into the adult years, i.e. some humans became lactose tolerant. We don't need milk to survive! There are plenty of people making it on a day-to-day basis without milk.

Dolphins and primates are generally accepted to be quite intelligent with some sort of self-awareness. Yet their intelligence is not even comparable to ours. They have other methods of survival... Would they some day be at the same level of humans?

So, is the human species really based on natural selection and/or evolution looking at its ability to survive - without looking at our ability to think?



[edit on 14-10-2005 by Gemwolf]

I'm not sure if I understand the question entirely, but I'd venture to say that humans aren't the best possible organism, they are no more 'evolved' than any other organism. But, in a sort of 'panglossian' way, since man is at the top of the food chain, man could be said to be the 'best', at least the 'ultimate' of what's actually out there.

Is the Human Species the ultimate designed lifeform.
In a word no.
For the egotistical argument then you could say that we are the best that is around now, but that is far from demonstrating that we are all that we could be.
The Human species is still evolving so is all the other life here on Earth. Who, what will prove to be the ultimate...... roll the dice!

I don't believe we are the "Ultimate" design, we are just the latest one, and it will be more.

If you compare the human species with the size of the universes we look nothing more than germs in grape.

No, we are not the "Ultimate design" but we are told that we are special.

[edit on 14-10-2005 by marg6043]

Originally posted by kenshiro2012

The Human species is still evolving so is all the other life here on Earth. Who, what will prove to be the ultimate...... roll the dice!

I find that hard to believe especially as now with technology, we let the "weak" still exist and try to accomodate them in our society. That is against natural selection, technology has actually helped us circumvent evolution to a large degree by letting imperfection to exist and instead of letting it eradicate itself we try to somehow manage it so that the person survives and they could pass on their gene. Because of that I feel that evolution has been circumvated to a large extent if not completely.
I dont know about other species but due ot human intervention many species that would otherwise thrive have been wiped out to extinction also some species that should have died out have survived due to human intervention.
Will their be a stage when humans will have the power to paint the canvas, so to speak?

Originally posted by Gemwolf
When we incorporate genetics into our story, it becomes more obvious why the generation of new variations is a chance process. Variants do not arise because they are needed. They arise by random processes governed by the laws of genetics.

Is evolution mostly chance or mostly adaption ?
Chance I agree has some influence but I thought that it was mostly adapting to the environment. Obviously evolution wouldnt make it such that one species had a tremendous advantage in its environment similar to giving the Polar bear a white nose as it can manage to hunt nevertheless and also the Panda's thumb, it is not at any serious disadvantage without it.

So, the question is, is the human body really the "perfect design" to survive and to be the top of the food chain?

I dont think we are the best of the best as yet but we are certainly up there. I wonder if evolution will lenghten and improve the co ordination of our fingers so we can use the computer better or some such adaption to cope with our mordern world? I wonder.

Don't get me wrong; the human body is really an extra-ordinary design with some amazing features. But there's so many "flaws".
For example why do we only have one set of teeth? Why not grow a new tooth when you loose a tooth like sharks? Back in the cavemen days they probably had bad hygiene - so by 60 they probably had little teeth left meaning you could only eat soft food.

Yeah thats a good question but if you notice chips they have good teeth even the older ones, but I've only seen them on Animal Planet so.....
I guess people had stronger teeth or had some mechanism to clean their teeth like my dog chews his bone for hours and thats supposed to be healthy for his teeth.

And while we're growing new stuff, why not the ability to grow a new limb like a lizard grows a new tail? If we came from the same gene pool - millions of years ago - then we should have had genes like that?

Maybe our limbs are too complex to regenerate like a lizards tail .

The human body is extremely fragile,..Was our ability to adapt and think creatively the only thing that saved the human species?

I certainly feel so, without our heads we are as good as chicken. But I guess our body must have been stronger before as we had a more physically demanding environment to live in.
If our bodies nad our brains developed at the same rate then we may have been like this super race or elves!

Originally posted by Gemwolf
So this sums up Natural selection (according to Darwin), right?

I believe so... but you DO realize that our understanding of evolution has changed a bit since Darwin, right?

BUT for natural selection to occur, two requirements are essential:
There must be heritable variation for some trait. Examples: beak size, color pattern, thickness of skin, fleetness.
There must be differential survival and reproduction associated with the possession of that trait. Unless both these requirements are met, adaptation by natural selection cannot occur.

Not necessarily. There's a lot of other BEHAVIORAL factors. Matings (particularly in the well-organized species) aren't the rape of the oblivious by the sex-driven lust-crazed other gender. Mating choice (even in fishes) is determined by behavior and a thousand other little traits. In addition to mating display choices, there's also social factors -- such as whether the animal is solitary or lives in groups or herds and at which age the young are sent off by the mother/parents to live independantly.

In addition, natural selection can only choose among existing varieties in a population.

There's also mutation brought about environment and/or radiation.

So, the question is, is the human body really the "perfect design" to survive and to be the top of the food chain?

No... but we have a limited sample of data. And if you're comparing h. sapiens without his or her tools and artifacts (clothing and housing) you'll see that we're not well adapted for killing prey (we'd have to run them off cliffs) or surviving temperature extremes.

The human body is extremely fragile, and our only defence against predators is brawn. Is that it? Was our ability to adapt and think creatively the only thing that saved the human species? If we grew poisonous tails like a scorpion to survive would this mean that we wouldn't have been so "smart"?

Not simple to answer. Remember we also have complex language and communication forms. We also have opposable thumbs and make tools to shape our environement to suit us rather than suffering chance.

And why are we so susceptible to diseases?

In fact, I recently wrote a paper on this and so I'm aware of the more current anthropological and archaeological data. Modern humans, in fact, aren't that susceptible to disease. Yes, it may LOOK like we are with all the scary news stories, but the truth is that we're not.

Primitive humans that live in small isolated groups have the weakest immune systems. When someone becomes sick, they can infect 20 people... but not that many more (if the whole camp is sick, they don't go running off to meet other people.) You were either dead or disease-free... and disease free simply because there weren't other people and animals living with you to cause disease spread.

When we started living in cities, it became possible for a single cold to spread to 800 people. When we kept animals with us, sometimes their diseases jumped the species barrier to us. Many died but the survivors had some resistance to the germs and a better immune system.

Look at HIV/AIDS. Look at how it's wiping out our species just because we can't find a cure. Back in "the old days" they didn't have any cures for illnesses like leprosy, pocks, etc. It's an endless list. BUT we survived all of that somehow. Why wasn't that survival mechanism kept in our immune system?

It's not wiping out our species. You're seeing a pattern of a new disease in a population that's not resistant to it. But we're already seeing cases where people ARE apparently immune to it... evolution in progress.

And when we "mutate"/evolve, we evolve the "stupid ability" to digest milk into the adult years, i.e. some humans became lactose tolerant. We don't need milk to survive! There are plenty of people making it on a day-to-day basis without milk.

You're seeing local adaptations to specialized diets, there, that evolved over many generations.

Dolphins and primates are generally accepted to be quite intelligent with some sort of self-awareness. Yet their intelligence is not even comparable to ours. They have other methods of survival... Would they some day be at the same level of humans?

Hard to say. They don't use tools or modify their environment significantly, so they're pretty far behind the curve on survability that way. I'd almost bet on the dog or the cat -- because they live with us, they adapt to our social patterns and we adapt to theirs. Many of them can operate our devices to some extent (including dogs that work for the disabled being able to call emergency services to come help their owners and cats that can open doors and refrigerators.) They eat our foods. I think the advantages of owning and being owned by the current top species on the planet is significantly altering their intelligence and their evolutionary pathway.

But I'm not sure I always want to know what my furry beasties are thinking!

Great stuff guys! Thanks.

...But I am surprised that no one has spoken about sharks, or fish like sturgeon or caleoanthicus (SORRY! sp.) - never mind cockroaches and other insects - or MICROBES..


There are numerous species that are FAR older, and more adaptable than man, and much more likely to "survive" - in Darwinian and other terms.

BTW - I agree with Byrd re adaptation and evolution in action - and would add that often, what we perceive as "disease" is actually adaptation, and part of the evolutionary process. Much as it might hurt,



.

Anyone who has knees and has participated in sport for any length of time KNOWS that we are NOT the Ultimate Design.

[edit on 18-10-2005 by Black Flag]

Thank you everyone for your input! One would never understand human development, evolution and survival on your own. Always good to hear other points of views!
(And thanks to IAF101 and Byrd for your extra effort! )
Byrd, you are obviously an expert on this topic, and I'd love to ask you a couple of questions on another occasion!
Just a couple of comments on your reply:
1. You say that HIV/AIDS is not wiping out the human race?
I don't agree with you on that one. The problem might not be as big in other countries like the USA, Europe, etc. but in Africa it's a really scary problem! Our government (referring to South Africa in specific) is hiding the actual stats from us and more specific from International media. Our president (Thabo Mbeki) is in complete denial over the illness. Ignorant so to speak. It has become that elephant in the corner. No one wants to talk about it because no one knows what to do about it. And the problem is snowballing. Once in a while they'll drop a random figure. 30% of our teachers are HIV positive. Our morgues are filling up. Cemeteries are running full. On death certificates it shows one or the other illness as cause of death, while it comes down to AIDS related illnesses. Byrd, the reality is - AIDS may not be wiping out the Human race, but it's wiping out Africa - and more specific people with a certain life-style.

2. I've never thought about domestic animals being the next in line for evolving to our level. But it makes complete sense!

3. I'm going to change my question a bit.
Keeping in mind what I said in my original post.
Does the human race really deserve to be at the top of the food chain?
Take away the last 5000 years of technology development. And make us again those "stupid" cavemen. Would we be just as successful the second time round? Keeping in mind the other "human" species that nearly made it to the top of food chain - like the Neanderthals - but disappeared "over night" while trying...

(I'm a Christian myself, but could we just be hypothetical here and say that God did not have a hand in this. Let's be scientific just for a second to let me try and understand the other side of the argument...)

Originally posted by Byrd

Dolphins and primates are generally accepted to be quite intelligent with some sort of self-awareness. Yet their intelligence is not even comparable to ours. They have other methods of survival... Would they some day be at the same level of humans?

Hard to say. They don't use tools

Actually there are groups of primates that use tools.

I've read about one group of chimps that have almost 20 tools ranging from chewed up leaves to dip into treeholes, and act like a sponge, to soak up water so that they can drink it; to certain rocks they use with divits to hold nuts so that they can strike them to crack the shell and eat the "meat".

news.nationalgeographic.com...
www.janegoodall.org...

There was even a recent thread here regarding an ape that used a walking stick to help balance with bipedal walking and to test water depth.

news.bbc.co.uk...

But yes, they are behind in the curve compared to us.

In regards to humans, modern medicine has ended natural selection for us.

Defects that would have shunned us from the tribe to fend for ourselves or killed us in the past are now coped with, or corrected through surgery, and in many cases these defective recessive genes responsible are now able to continue to propagate. Not for the betterment of our species but for the love we have for those close to us and our not wanting to "lose" them.

Gemwolf
Does the human race really deserve to be at the top of the food chain?

I don't believe any creature "deserves" to be at the "top", but that there should be a balance in nature.

That said, brains over braun wins and if everything were "reset" I believe we would rise to the top again.

The capacity of the human mind is astounding and even now we still only use roughly 10%.


[edit on 10/19/05 by redmage]

Actually, we use closer to 100% of our brain capacity.

However...

The "10%" number is somewhat accurate.

Current PET and MRI technology show evidence that we use about 10% of our brain AT ANY GIVEN TIME.

It may seem nitpicking, but it is actually more significant than that.

ps: Even birds have been witness to use tools - for what it's worth.

Here's an interesting little tid-bit on animals not only using, but also making tools.

But observation has confirmed that monkeys and other animals, mostly primates, but also some birds (ravens, for instance), and sea otters can use tools as well. Later, philosophers thought that only humans have the ability to make tools, until zoologists observed birds[1] and monkeys[2][3][4] making tools. Most anthropologists believe that the use of tools was an important step in the evolution of mankind. Humans evolved an opposable thumb (useful to hold the tools) and an increase in intelligence (aiding in the use of tools).

en.wikipedia.org...