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Elephants Never Forget nor get Cancer

2015-10-08

Have you ever wondered if elephants get cancer?  Well, they don’t, and two research papers out recently suggest why elephants are resistant to cancer.  There is a gene, TP-53, that is critical to cell mechanisms for cancer resistance.  This gene is involved in triggering apoptosis, or programmed cell death, in response to damage in the cell’s chromosomes or critical cell machinery.  Humans have one (paired) copy of this gene, and elephants have at least 20 copies, all of which have evolved to increase the cell’s sensitivity to important injuries.  The elephant cell is more likely to undergo apoptosis and die off in response to injuries that could result in mutations and uncontrolled cell growth.

As a result of their advanced immune systems, elephants have a cancer death rate of less than 5%.

What about human death rates from cancer?  Out of 2.5 million deaths in the US in 2013, 584 thousand were from cancer, or about 22%.  Heart disease was the leading cause of death, with 611 thousand, while “chronic lower respiratory disease” claimed 149 thousand.  Accidents beat out stroke, with 130 thousand versus 129 thousand.  Alzheimer’s Disease, diabetes, influenza and pneumonia, kidney disease each got between 84 thousand and 49 thousand,  and finally suicide, with 41,149 deaths.

So there is plenty of room for improvement in the human genome, although the improvement in this case will involve much more than simply increasing the number of TP-53 genes.  In the future we may be able to lift sections of the genomes of certain advanced animals for our own use.  That is, in addition to the genes that we will synthesize to improve on normal functions or add new functions.

There is no reason to think that our evolutionary advancement in cerebral capacity is matched by advancement in all other capacities.  For example, our tender skins are unprotected by any fur, and our nails are pitifully inadequate in a fight.  Our muscles are far less powerful than those of the chimpanzee, and we cannot run as fast as a horse nor climb a tree like a monkey.  In muscle strength alone, we have seen mutations in both man and animals that increase muscle mass by blocking myostatin (a newly discovered hormone that regulates muscle growth.)

The only advantage we really have is the size of our brains and the quality of our thoughts.

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