All posts tagged: males

A single gene may explain why some males live fast and die young

A single gene may explain why some males live fast and die young

Published by Jenni Sidey

A small fish that lives fast and dies young has given biologists a rare look at one of evolution’s oldest bargains. In the African turquoise killifish, researchers traced that bargain to a single gene called vgll3, which helped push males toward faster growth and earlier sexual maturity. But the same shift also came with a darker side: shorter lives, more age-related tumors, and a higher risk of melanoma-like cancers in old age. The finding offers unusually direct evidence for antagonistic pleiotropy, a long-debated theory of aging that holds that some genes are favored because they improve early-life success, even if they cause damage later on. “We have effectively caught evolution in the act of making a trade-off,” said Dr. Itamar Harel of Hebrew University. “For years, we’ve asked why our bodies can’t just maintain themselves indefinitely. This gene gives us a direct answer: nature doesn’t prioritize longevity; it prioritizes continuity. We are built to sprint, not to marathon.” The killifish is an emerging model for investigating the genetic architecture of aging and age-related pathologies, which …

Bull sharks make ‘friends’—and prefer females to males

Bull sharks make ‘friends’—and prefer females to males

Published by Jenni Sidey

Get the Popular Science daily newsletter💡 Breakthroughs, discoveries, and DIY tips sent six days a week. Bull sharks (Carcharhinus leucas) have a really bad reputation. The ocean’s bad boys are responsible for at least 100 unprovoked attacks on humans, 27 of which have been fatal. However, the species may be responsible for more attacks. A bull shark was likely behind the real encounters that inspired the award-winning novel and film Jaws.  However, these 12-foot-long, solitary sharks appear to form important social bonds. A study published today in the journal Animal Behaviour finds that they create these relationships with only a few specific “friends.” Instead of mixing at random, they appear to actively choose who they spend time with and have preferences. “As humans we cultivate a range of social relationships—from casual acquaintances to our best friends, but we also actively avoid certain people—and these bull sharks are doing similar things,” Natasha D. Marosi, a study co-author and founder of Fiji Shark Lab, said in a statement.  Over six years, a team from the University of …

Neanderthal males preferred human females, genetic study finds

Neanderthal males preferred human females, genetic study finds

Published by Jenni Sidey

Thin stretches of the human X chromosome look oddly empty when you scan for Neanderthal DNA. Geneticists even have a name for the gaps: “Neanderthal deserts.” They sit there like blank tape in an otherwise crowded recording. For years, the standard story went like this: Neanderthal DNA landed in our ancestors’ genomes. However, some of it was harmful, especially on the X chromosome. Natural selection, the thinking said, gradually stripped those “toxic” variants away. A new analysis from Sarah Tishkoff’s lab at the University of Pennsylvania argues that the emptiness may say more about who paired with whom than which genes were dangerous. In Science, the team reports a mirror-image pattern inside Neanderthal genomes. Neanderthals carried unusually high levels of modern human DNA on their X chromosomes compared with the rest of their genome. That reversal, they say, makes simple “toxicity” a much harder explanation to defend. The deserts and the old assumption “Along our X chromosomes, we have these missing swaths of Neanderthal DNA we call ‘Neanderthal deserts,’” says Alexander Platt, a senior research …

Everyone’s a queen: The ant species with no males or workers

Everyone’s a queen: The ant species with no males or workers

Published by skeptic

Temnothorax makora ants are parasitised by the related species Temnothorax kinomurai clurarit/iNaturalist A parasitic species of ant from Japan is the first ever found to have done away with both males and female workers – instead, every individual is a queen that tries to take over the nests of other species. Typically, ant colonies consist of a queen, female workers and short-lived males that die after mating. For more than 40 years, researchers have suspected that the rare parasitic ant Temnothorax kinomurai only produces queens, but until now there has been no definitive proof. Young queens of this parasitic species take over the nests of a related species, Temnothorax makora, killing the host queen and some workers by stinging them. They then reproduce asexually, producing cloned offspring in a process called parthenogenesis, which is rare in ants but common among some other insects. The T. makora workers are duped into helping raise the young T. kinomurai queens. Jürgen Heinze at the University of Regensburg, Germany, and his colleagues collected six colonies with T. kinomurai queens …