Adam's Curse: A Future Without Men (also known as Adam's Curse: A Story of Sex, Genetics, and the Extinction of Men) is a 2003 book by Oxford University human genetics professor Bryan Sykes expounding his hypothesis that with the declining sperm count in men and the continual atrophy of the Y chromosome, within 5,000 generations (approximately 125,000 years) the male of the human species will become extinct.
Sykes believes one of the options for the survival of humanity is unisex reproduction by females: female eggs fertilised by the nuclear X chromosomes of another female and implanted using in vitro fertilisation methods. He also introduces the possibility of moving the SRY and associated genes responsible for maleness and male fertility to another chromosome, which he refers to as "the Adonis chromosome", engendering fertile males with an XX karyotype.
||This section possibly contains original research. (March 2013)|
The Y chromosome may wither to the absolute minimum needed to sustain reproduction, but no more, because a chromosome that won't breed won't be carried to its descendants - therefore, only functioning Y chromosomes will be passed on to future generations, and obviously no infertile men will transmit any Y chromosomes causers of infertility. Female infertility is also strangely[clarification needed] forgotten in the work.
A further point of contention is that declining sperm counts have been linked to industrialisation, with environmental toxification as the presumed mechanism. If this is indeed the cause, then there is no reason to believe that a solution to the pollution problem won't also lead to a return to historical levels of male fertility.
More recent research (discussed at the end of the book) has shown that the Y-chromosome is capable of self-repair. In any case, it is impossible to assure that Y chromosomes won't evolve in any other way than self-repairing or extinction.
It can be noted that the Dunnart has a Y chromosome that has shrunk to only 4 genes, the smallest of any mammal, with no apparent ill effect.