Sex differences in human physiology
Female fertility declines after age 30 and ends with the menopause. Female physical experiences vary depending on external forces such as diet, marriage patterns, culture, and other aspects. In Western nations menstruation begins to affect females at 13 and menopause starts around 51. In non-industrialized countries, on the other hand, most females begin menstruation at a later age. More lactation in the lifetime of non-western females inhibits ovulation and extends the number of fertile years. Pregnancy in the 40s or later has been correlated with increased risk of Down syndrome in the children. Males are capable of fathering children into old age. Paternal age effects in the children include multiple sclerosis, autism, breast cancer and schizophrenia, as well as reduced intelligence. Adriana Iliescu was reported as the world's oldest woman to give birth, at age 66. Her record stood until Maria del Carmen Bousada de Lara gave birth to twin sons at Sant Pau Hospital in Barcelona, Spain on December 29, 2006, at the age of 67. In both cases IVF was used. The oldest known father was former Australian miner Les Colley, who fathered a child at age 93.
Menopause
While it is fairly common for extant hunter-gatherers to live past age 50 provided that they survive childhood, fossil evidence shows that mortality in adults have decreased over the last 30000 to 50000 years (possibly due to innovations relating to defense from large carnivores and/or decrease in the ratio of large carnivores to humans) and that it was extremely unusual for early Homo sapiens to live to age 50. This discovery have led some biologists to argue that there was no selection for or against menopause at the time at which the ancestor of all modern humans lived in Africa and had not split into different ethnicities, suggesting that menopause is instead a random evolutionary effect of a selection shadow regarding ageing in early Homo sapiens. It is also argued that since the population fraction of post-menopausal women in early Homo sapiens was so low, menopause had no evolutionary effect on mate selection or social behaviors related to mate selection.