Why humans lack an 'anti-aging switch'

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You may have seen the news that the human lifespan cannot be extended beyond about 115 years, as shown by a demographic analysis confirming that the steady improvements in lifespan seen for many populations over recent decades has stalled since the 1990s.http://feeds.feedburner.com/~ff/rss/cnn_us?d=yIl2AUoC8zA</img> (http://rss.cnn.com/~ff/rss/cnn_us?a=yz_iIrTcO5Q:7zCE36jqjmM:yIl2AUoC8zA) http://feeds.feedburner.com/~ff/rss/cnn_us?d=7Q72WNTAKBA</img> (http://rss.cnn.com/~ff/rss/cnn_us?a=yz_iIrTcO5Q:7zCE36jqjmM:7Q72WNTAKBA) http://feeds.feedburner.com/~ff/rss/cnn_us?i=yz_iIrTcO5Q:7zCE36jqjmM:V_sGLiPBpWU</img> (http://rss.cnn.com/~ff/rss/cnn_us?a=yz_iIrTcO5Q:7zCE36jqjmM:V_sGLiPBpWU) http://feeds.feedburner.com/~ff/rss/cnn_us?d=qj6IDK7rITs</img> (http://rss.cnn.com/~ff/rss/cnn_us?a=yz_iIrTcO5Q:7zCE36jqjmM:qj6IDK7rITs) http://feeds.feedburner.com/~ff/rss/cnn_us?i=yz_iIrTcO5Q:7zCE36jqjmM:gIN9vFwOqvQ</img> (http://rss.cnn.com/~ff/rss/cnn_us?a=yz_iIrTcO5Q:7zCE36jqjmM:gIN9vFwOqvQ)
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