- Reaction score
- 1,697
The oldest-known sex chromosome emerged in octopus and squid between 455 million and 248 million years ago — 180 million years earlier than the previous record-holder, scientists have discovered.
The oldest known sex chromosome in animals has been discovered, pushing back the date for the evolution of sex chromosomes to between 248 million and 455 million years ago.
The ancient chromosome was found in octopus and squid, suggesting that these may have been among the first animals to determine their sex via genetic blueprint, instead of environmental cues.
Sex chromosomes are standard in mammals. In humans, the sex chromosomes are X and Y. Males usually have an X and a Y chromosome, while females have two Xs, although there are some variations, such as XXX or XXY, which can have a wide range of impacts from no effect at all to certain learning disabilities or neurological differences.
For a long time, researchers weren't sure whether cephalopods, the soft-bodied mollusks that include squid and octopuses, determined their sex with chromosomes. Mollusks have a variety of ways to handle reproduction, including hermaphroditism or sequential hermaphroditism, in which individuals swap sexes over time.
www.livescience.com
The oldest known sex chromosome in animals has been discovered, pushing back the date for the evolution of sex chromosomes to between 248 million and 455 million years ago.
The ancient chromosome was found in octopus and squid, suggesting that these may have been among the first animals to determine their sex via genetic blueprint, instead of environmental cues.
Sex chromosomes are standard in mammals. In humans, the sex chromosomes are X and Y. Males usually have an X and a Y chromosome, while females have two Xs, although there are some variations, such as XXX or XXY, which can have a wide range of impacts from no effect at all to certain learning disabilities or neurological differences.
For a long time, researchers weren't sure whether cephalopods, the soft-bodied mollusks that include squid and octopuses, determined their sex with chromosomes. Mollusks have a variety of ways to handle reproduction, including hermaphroditism or sequential hermaphroditism, in which individuals swap sexes over time.
Oldest known sex chromosome emerged 248 million years ago in an octopus ancestor
The oldest-known sex chromosome emerged in octopus and squid between 455 million and 248 million years ago — 180 million years earlier than the previous record-holder, scientists have discovered.
www.livescience.com
