reply to post by RBinOkc
Doesn't evolution make us bigger, faster, and stronger?
Evolution is simply change from one form to another. The direction of change depends on the conditions of the surrounding environment.
The engine driving most of this change is called natural selection. This is simply the principle that living things live longer and have more
descendants if their physical form and behaviour are well suited to take advantage of their surroundings. That only rarely means being the biggest,
fastest or strongest thing in it. It could just as well mean being the smallest or the slowest. What use is size to a hummingbird? What use is speed
to a blue whale?
If, in a species, bigger, faster and stronger individuals tend to live longer and have more babies, then natural selection will
development of those traits. But stop and think for a minute. Where are the size, speed and strength going to come from? Nature gives no free lunches.
There has to be adequate energy in the environment – in the form of food, sunlight, whatever it is the organism consumes – to support the
development of stronger muscles, bigger bones, etc. This places a limit on development.
When resources are scarce, size, strength and speed can actually be harmful
to survival. Think of a lion. There he is out on the African
savannah, lord of all he surveys, perfectly suited to his environment. As long as the antelope are running, he's in clover. But now imagine a long
drought – a drought that dries up the waterholes and kills the kudu and the springbok in droves. What price now the size, strength and speed of the
king of the jungle? That massive, bulky body may not find enough food to sustain it until the rains come. Meanwhile, Big Leo's leaner, smaller
competitors, the hyenas and wild dogs, scrape a living through the drought, and when the rains return they will mate and fill the world with their
The traits that best support survival and reproduction always
depend on how the organism interacts with its environment. Size is good for an
animal that needs to fight against others of its kind (in mating contests and so on) but in the battle for survival it is often a liability. Speed
sounds like an obvious all-round advantage, but animals that live in very cold climates (or very dry ones) often conserve energy by slowing down or
hibernating. Narwhals, which live among the ice-floes of the Arctic, are among the slowest of all mammals in terms of their muscle movement and
There are evolutionary situations in which it helps to be small, slow, weak and even stupid. Living beings have exploited all these situations.
Sloths, tortoises and snails do pretty well out of slowness, don't they? Haven't jellyfish and hydras colonized all bodies of water on Earth without
ever needing to evolve a brain? Remember, the most successful terrestrial organisms of all are bacteria – now there's
something to make us
proud humans stop and think!
Won't things like goosebumps and wisdom teeth be eliminated by evolution since we as humans have no need for them anymore?
Yes, because – as we have seen – the amount of energy and other resources available to an organism is limited, and spending it on traits lacking
survival value means depriving other, more useful traits of energy. This weakens the organism and makes it relatively more likely to be eliminated
from the gene pool before it can reproduce.
Over time, natural selection will tend to eliminate superfluous physical or behavioural traits. But environments also change over time; today's
essential survival trait may become tomorrow's evolutionary leftover, and vice versa
. My screen name is shared by a species of blind cave fish
whose ancestors once had eyes. Has the fish 'devolved' because it is blind? Or has it evolved to become better suited to its environment, abandoning
altogether the attempt to preserve its useless eyes and spending the energy saved by this on something more useful to a blind cave fish – a more
sensitive lateral line
Won't we eventually over millions of years become "super human' or a race that will live forever?
If I have explained the subject well enough above, you now understand why this cannot happen. Evolution is not a steady upward progress towards an
ideal of perfection. It is just change.
Another question I have is does DNA evolve and if so wouldn't that make my question even more valid?
Yes, DNA evolves. All evolution is, in the end, evolution of DNA.
edit on 5/4/12 by Astyanax because: of naturah serectono