Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
Natural selection is a process which directs all biological evolution. It is a process that directs genetic changes which when proved to be adapted to the environment are retained in the genome. In other words, man like any other organism may have to passively adapt lo changing ecological circumstances through a slow, generation by generation change in gene complexes. The question is, does natural selection act in the same way in man as it is acting on other organisms. The major difference between man and other organisin is that man is capable of steering his own evolution whereas the other organisms cannot. Teilhard de Chardin, an eminent human paleontologist and anthropologist says "the evoluton of life on earth, far from having come to a stop, is on the contrary now entering a new phase. The Darwinian era of survival by natural selection is thus succeeded by a Lamarkian era of super life brought about by calculated invention". Such a statement gives credence to the hypothesis that man can monitor his own evolution in future.
There is evidence to suggest that man through the technological revolution has modified the role of natural selection. As an example one may mention the cancer of the eye, the retinoblastolna caused by a dominant mutation. The disease develops as a tumor in one of the eyes of the affected child, spreads to the other eye and then extends to the brain causing the death before the individual reaches the adulthood. Today, if the condition is detected sufficiently early, it is possible to remove the tumor surgically despite the loss of one eye. The child can grow into a near normal adult, marry and give birth to children. But there is a 50% chance for his children to be born with retinoblastoma. And inturn they have to be treated for the disease. Here is an instance where, through a surgical treatment a lethal gene is permitted to be preserved and passed on to the subsequent generations. Natural selection in normal course would have aimed to eliminate the gene from the population. But if the lethal condition were to be completely cured in every patient the frequency of the gene would increase slowly in the population.
Hydra – Metazoa The animals of phyla Cnidaria and Ctenophora are made up of only two germ layers: ectoderm which forms the outer covering of the animal and endoderm which is t
Q. Demonstration of tremendous diversity? A objective of taxonomy is the assemblage of knowledge gained. This is usually in the form of treatises useful to fellow scientists an
classification of phylum protozoa upto groups
Nuclear transport is an energy-dependent process mediated through saturable receptors. Export and Import receptors are by to distinguish and bind to nuclear localization signals or
A protein that is normally a single-pass transmembrane protein is absent from the cell surface of the mutant cell line YTM-15. When labeled so that the protein can be localized, yo
Q. What are examples of the economic and ecological importance of molluscs? Molluscs are important players in several food chains in ecosystems. Many marine molluscs are part o
Define Factors Which May Lead To Errors in Count? There are many factors, which may lead to errors in count. (i) Counts may be low if the agar medium used in the technique d
Prevention of flap necrosis Flap necrosis can be prevented if the surgeon attends to four basic principles. 1. First, the apex of a flap should never be wider than the base,
Define Reagent for Separation of Amino Acid by Paper Chromatography? The following reagents will be required for carrying out the experiment: 1. Amino acid solution- Weig
What happens to respiratory system in a man going up a hill?
Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd