Normal anxiety is considered an adaptive response to the possible presence of danger, but it appears highly susceptible to dysregulation. Anxiety disorders are prevalent at high frequency in contemporary human societies, yet impose substantial disability upon their sufferers. This raises a puzzle: why has evolution left us vulnerable to anxiety disorders?
Over five million children have been conceived by assisted reproductive technology (ART) since the first live birth from in vitro fertilization in 1978. ART babies represent >1% of babies in the USA, >2% in Japan and >3% in Australia.
Comparative medicine has a long and strong tradition, in which studies of naturally occurring diseases in other animals has shed much light on the origins and pathophysiology of human ailments. Less attention has been paid to the flip side of the coin, i.e., are there diseases that are preferentially or uniquely human?
Early life experiences can dramatically affect traits expressed in adulthood, but the evolutionary origins of such effects are debated. The ‘predictive adaptive response’ hypothesis argues that adverse early environments prompt adaptive phenotypic adjustments that prepare animals to cope with similarly adverse environments in adulthood.
Cancer can be understood as a problem of cheating in the multicellular body. In cancer, certain cells of the body enhance their fitness at the expense of the organism as a whole. The evolution of multicellularity represents a highly sophisticated form of cooperation and cheater suppression.