Thread: Theory of evolution

We have studied Darwin's theory of evolution that evolution is on going process. But atleast in the past 2000 yrs(i.e., from Jesus Christ to till date) the physical form of man and other animals have remained same. Does the theory stand even now?

In 2000 years there have been somewhere between 70-150 generations of humans. Nowhere near enough for any visible, functional genetic transformation to have eventuated.

For all we know there are mutations or latent functions within our genome that will only ever express or become relevant when the population has to deal with a major stress. Worldwide disease, famine, climate, war, volcanic catastrophe, a major meteor strike would destroy significant portions of the population pool. It will be a nasty chance if it turns out that those were the people with the genetic fitness to deal best with the consequences of whatever it is.

But no. The theory of gradual, imperceptible change when no stressors influence genetic selection holds. We, or our descendants. may yet get to see what does or doesn't happen in a highly stressed environment - famine would be the most likely one in my view. But the flu virus can always catch us unawares with significant changes in both virulence and transmission rates simultaneously. (That was the big fear with bird flu a couple of years ago. That it would transmit human to human, it was virulent enough to kill millions of us if it had.) Whether this or any such significant event would pose noticeable evolutionary pressure is a question we could only answer after the event.

Originally Posted by VARADRAJ

But atleast in the past 2000 yrs(i.e., from Jesus Christ to till date) the physical form of man and other animals have remained same. Does the theory stand even now?

Are you so sure ? Obviously, many animal and vegetal species have disappeared during the last 2000 years. Probably, a few new species have appeared (new viruses for instance). About men, I can imagine that some characteristics may have developped or regressed : for instance, the proportion of the population with blue eyes and clear skin may be different now than 2000 years ago.
It seem's that actual population is taller than previous generations. This may be a consequence of an improvement in food quality ... it may be, partly, a consequence of evolutions : girls prefer to mate with tall and strong guys.

Originally Posted by VARADRAJ

We have studied Darwin's theory of evolution that evolution is on going process. But atleast in the past 2000 yrs(i.e., from Jesus Christ to till date) the physical form of man and other animals have remained same.Does the theory stand even now?

Darwin recognised from the outset that evolutionary change would be necessarily slow. This is why he devoted a considerable period of his life to researching artificial selection of domesticated animals and why a substantial portion of On the Origin of Species was focused on this. He clearly demonstrated that under the direction of man that evolutionary changes can and do occur rapidly. He asserted that natural selection would have a comparable effect, but might require more time (generations) to operate for a comparable change.

In regard to human evolution I recommend you read this review article for a clearer understanding of the ongoing evolution of humans. (Laland et al " How culture shaped the human genome: bringing genetics and the human science together." Nature Reviews Genetics volume 11 2010)

just google "evolution in action" and you'll see that there's plenty of examples of change even over short time periods
the change may not always be immediately visible or obvious, but if you know what you're looking for, it is there

a few that i've just picked after a quicke google :

7 signs of evolution in action
Evolution in Action: Lizard Moving From Eggs to Live Birth
8 Examples of Evolution in Action
Evolution (+ click on the "Evolution in Action" button)

etc.etc.