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.
Products of Cleavage (Morula and blastula) In several cases, the blastomeres in early cleaving stages tend to presume spherical shape like that of the egg earlier than cleava
Explain Coarctation of Aorta ? Coarctation of aorta may be isolated or it may have other co-existing cardiac and vascular lesions. In critically ill neonates with coarctation,
Define Nutritional Requirements in Cold and Polar Environment? Energy requirements are the major consideration for providing nutritional support in a cold environment. Energy e
Resistance to Isoniazid The most common pattern of resistance is isolated resistance to isoniazid, which can be treated with rifampin, pyrazinamide and ethambutol for 6-9 mont
CYTOCHEMISTR Y OF PROTOPLASM - It is supper mixture or mixture of mixtures . 3 4 elements present in it. 1 3 elements are universal. e.g. C, H, O, N, P, K, S,
Explain Membrane Filtration Technique? Another method used for determining the bacterial number is the filtration technique. The margain figure illustrates the membrane filter
Results: The risk of isolated aortic valve replacement is 3-4 per cent. The long term survival for 5, 10 and 15years is 75 per cent, 60 per cent and 40 per cent respectively. The
Explain water Universal Solvent ? Water - Universal Solvent : Water is usually referred to as the "universal solvent." because it is able to dissolve many different substan
Haustorial variations
What are the antigens and the respective antibodies of the ABO blood group system? The ABO blood system contain the erythrocytic antigens A and B that can be attacked by the an
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