Why Chimpanzees Have Big Testes, and Mandrills Have Small Ones
Why Chimpanzees Have Big Testes, and Mandrills Have Small Ones
For primates, males’ fancier ornaments are linked with smaller testes, according to a new comparative study.
Why Chimpanzees Have Big Testes, and Mandrills Have Small Ones
Why Chimpanzees Have Big Testes, and Mandrills Have Small Ones

For primates, males’ fancier ornaments are linked with smaller testes, according to a new comparative study.

For primates, males’ fancier ornaments are linked with smaller testes, according to a new comparative study.

reproduction
Image of the Day: Sperm Donors
Image of the Day: Sperm Donors
Carolyn Wilke | Mar 18, 2019
Asexual female nematodes use their male offsprings’ sperm to fertilize eggs, but cast away their genes.
Doctors Report World’s Second Case of “Semi-Identical” Twins
Doctors Report World’s Second Case of “Semi-Identical” Twins
Catherine Offord | Feb 28, 2019
The extremely rare event, thought to be caused by two sperm cells fertilizing the same egg simultaneously, was last reported in 2007.
Image of the Day: Self-Insemination
Image of the Day: Self-Insemination
Carolyn Wilke | Feb 1, 2019
Videos reveal how a female squid fertilizes her eggs—one at a time and without spilling much stored sperm.
Image of the Day: Surprise!
Image of the Day: Surprise!
Kerry Grens | Nov 21, 2018
A 37-year-old simiang gibbon on birth control unexpectedly gave birth at the San Diego Zoo.
Image of the Day: Plundered Plover
Image of the Day: Plundered Plover
Jef Akst | Nov 9, 2018
Nest predation of shorebirds that raise young in the Arctic are up threefold since the mid-20th century, and climate change may be to blame, according to a study.
Fishy Behavior: Prof Allegedly Profited from School Caviar Sales
Fishy Behavior: Prof Allegedly Profited from School Caviar Sales
Ashley P. Taylor | Oct 29, 2018
A University of Georgia fisheries researcher, who is head of the school’s program to farm-raise sturgeon and sell their salt-cured eggs, is expected to retire this week.
Genetic Risk Factor for Erectile Dysfunction Identified
Genetic Risk Factor for Erectile Dysfunction Identified
Ashley P. Taylor | Oct 9, 2018
Researchers believe the genetic locus affects the regulation of another gene involved in sexual function.
Image of the Day: The Long and Short of It
Image of the Day: The Long and Short of It
Sukanya Charuchandra | Aug 20, 2018
For flycatchers, the attractiveness of male birds is tied to the length of their sperm.
Bioethics Council: Gene-Editing Human Embryos Conditionally OK
Bioethics Council: Gene-Editing Human Embryos Conditionally OK
Shawna Williams | Jul 17, 2018
The UK-based organization encourages public debate about the issue but does not recommend immediate policy change.