Natural selection is the mechanism the biological world is constantly being worked through. The species that has more survival advantages will continue on to spread their genetic material through the gene pool. Those that have disadvantageous changes will be weeded out giving way for the old saying, “survival of the fittest”.
“Life results from the non-random survival of randomly varying replicators.” – Richard Dawkins
For instance, imagine a group of birds that ingests mainly berries and insects and another group of birds with the ability to ingest the high protein and fat rich grubs that live inside branches of trees. As time goes on the birds surviving off of high protein and grubs become adapted to getting deep into the bark for their food source. Soon, as evolution takes place, their beaks grow longer, stronger, and better designed for digging. Not only have they now adapted to this change but our first group of birds, the ones that survive on berries and insects, have begun to notice their food source is not as reliable. Natural selection is favoring the birds with evolved beaks and this process of weeding out the inefficient beak shapes allows for variation among the bird kingdom.
I say this as a preface to the post as a brief overview for how important the process is. It is this essential biological process that is responsible for the immense variation of life we have on this planet.
Four billion years of this process has brought us to the point in time when we have human beings running the planet and breeding in a manner that over rides natural selection. Take for instance the large ethnic diversity among our species at this point in time. These ethnicities evolved over the last 200,000 years in many isolated areas on the planet. With our ever expanding culture shift towards a single human sphere of always connected people we are starting to revert the progress of that process back into a single Human Ethnicity. While I doubt ethnicities will ever completely merge into a single ethnicity we are starting down a path that will inevitably remove the distinctions amongst the peoples of earth and create a single “human” appearance. No longer will humans live in complete isolation from each other.
Not only are ethnicities in danger but our species’ ability to weed out vestigial organs and our natural evolution away from chimpanzees has been slowly eradicating our tailbone. As far as vestigial organs most are likely to stick with us for the distant future. The appendix, for example, is a vestigial organ that is often removed from humans around their second decade of life. Natural selection would have taken care of this by allowing those with such problems to die and stopping them from being able to procreate at the same rate those with working appendix or shrinking appendix would have. Therefore due to our foray into a technological civilization with medical care we have created a system that allows for those with the faulty genes for exploding appendixes to survive and breed at the same rate as those without those genes. This sets up a precedent that allows for “junk” DNA to continue to exist in the gene pool.