Access
This article is part of Nature's premium content.
Published online 26 January 2009 | Nature | doi:10.1038/news.2009.55
News
Humans and sponges may share a slimy ancestor
Placulan origin re-roots the tree of life.
Organ-less, slime-like creatures just a few millimetres wide could be the ancestors of both sponges and humans, according to new research. But the findings are proving contentious, not least because they suggest that the nervous system evolved twice.
To read this story in full you will need to login or make a payment (see right).
Comments
Reader comments are usually moderated after posting. If you find something offensive or inappropriate, you can speed this process by clicking 'Report this comment' (or, if that doesn't work for you, email webadmin@nature.com). For more controversial topics, we reserve the right to moderate before comments are published.
Humans, sponges, indeed all metazoans, share the ability to synthesize collagens. These structural proteins require two amino acids not in the genetic code...hydroxyproline and hydroxylysine. I don't think that the Placozoa have either of these, although some fungi do, as does Volvox. It seems fair to ask how a placozoan lacking the complex pathways involved in the biosynthesis of these post-translational amino acids required for collagen could be a common ancestor for those that do.... the other similarities notwithstanding.