Tag Archives: Darwin

Evolution and Humans

This post was written on Friday, March 06, 2009

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We all know about Darwin’s theory of natural selection and how it affects the evolution of species. According to Darwin’s theory, individuals better adapted to the environment produce more offspring. This causes their traits to pass on. The individuals that have traits that are less suitable for the environment produce less offspring and these traits decrease over generations and finally die. It is thus the survival of the fittest( or best adapted).

Does evolution apply to us humans? Are we still evolving according to the laws of natural selection? Do we still select the fittest amongst ourselves and not let the less pass on their genes? These are the questions that we will try to answer in this VERITAS. And these are not easy
questions- we are the only animals that know what evolution is and this knowledge adds an interesting dimension to these questions. Can we use this knowledge to evolve according to a plan?

Humans have not stopped evolving. We know that Homo Sapiens originated in Africa  about 200,000 years ago. They spread across the world about 50,000 years ago and replaced the existing humanoid populations in Europe and Asia. About 15,000 years ago, during the last ice age, as the ice sheets expanded and the sea levels fell, they crossed over to the Americas through the Bering Strait land bridge.
So we all come from a common origin- we all started with the same genes. But as we can see, people in different parts of the world look different, have different colors, have different heights, are prone to infections from different diseases. This is because of natural selection.

Let’s take some examples of how environment has shaped human evolution. People living in places that have less sunlight have fair skin. This is because fair skin absorbs ultraviolet radiation better compared to darker skin. This helps people living in sunlight deprived regions get adequate vitamin D.
So though we all have a common ancestor, people living in different parts of the world  have different skin colors to suit their own environment. Take another example: lots of people in east Asia cannot digest milk in adulthood. This is because they lack a digestive enzyme responsible for lactose digestion. But most people in Europe have this enzyme and thus milk, cheese etc are a regular part of their diet.Thus we see that culture of what we eat and what animals we keep has also influenced evolution. One last example: some populations in Africa are resistant to malaria. Since mosquitoes are found in plenty in Africa, this resistance offered survival and therefore reproductive advantages causing the evolution
of the whole population to have this resistance.

So we are evolving. Local environments challenge us and the genes that are best suited for these environments pass on to future generations. But there is nothing uniquely human in patterns of evolution that I have just described. Different sets of animals when placed in different environments will evolve differently. So if we were to separate Asia, Africa, America and Europe from each other for 20,000 years we may all
evolve into different species- each perfect in its own environment but completely different from the other and unable to reproduce with the other species. The reason why Humans are still one species is because we travel and we marry people from different parts of the world. If we are to remain one species it is important that we realize that racial groups should not have barriers for inter-marriage and reproduction.
We have to mix with each other and have inter-race children if we are to prevent a speciazation of different human populations.

Natural selection is cruel. Individuals not well adapted to the environment die or are unable to produce offspring. That is how it happens in animals and that it how it happened for humans. But we are now a more civilized species. We care for everyone. Medical science has given almost everyone the chance to enjoy a long life and be able to reproduce. Now, this also means that harmful genes do net get weeded out by evolution. And that is not good for the human population as a whole.

Also, in some cases people carrying less useful genes tend to have more offspring. Intelligence is a classic example of this. People with a high IQ tend to study more, marry late and have less offspring. People with lesser IQ study less, marry early and tend to have more children. Would this cause the average human intelligence to decrease over generations?

Thus we face a dilemma: We have evolved into a civilized society in which we care for everyone. Thus our social fabric does not let the cruel hands of natural selection weed out the bad/less useful genes. But we do value certain characteristics like intelligence and good health and want them to  improve over time. How do we achieve this goal without letting natural selection take control?

The answer lies in Genetic Engineering. Using genetic engineering we can let everyone have children but without the bad genes. With genetic engineering we can evolve into more developed species without letting natural selection take control. With genetic engineering we can become more intelligent over generations without having to ask our high IQ friends to produce more kids than their neighbors.

In my opinion genetic engineering can help us achieve the aim of evolution without natural selection. But it has to be done very carefully and in a manner that is fair to everyone and also ethical. And it has to be done after sound research into the effects and side-effects of modifying each gene.

Our future is not in the hands of natural selection but in the hands of modern science which would exercise selection over genes and not over people.

Kanwar

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Go, wondrous creature! mount where Science guides:
Go, measure earth, weigh air, and state the tides:
Instruct the planets in what orbs to run,
Correct old time and regulate the Sun;
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