Man's oldest ancestor

Humankind evolved from a bag-like sea creature which had a large mouth and no anus, scientists have said.

The microscopic creature, named Saccorhytus, lived 540 million years ago, and was discovered in microfossils found in China.

About a millimetre in size, scientists believe it ate by engulfing food particles and got around by wriggling.

But scientists were unable to find any evidence the animal had an anus.



Simon Conway Morris, of the University of Cambridge, said: "If that was the case, then any waste material would simply have been taken out back through the mouth, which from our perspective sounds rather unappealing."

Living between grains of sand on the sea bed, the creature is thought to be the most primitive example of a so-called "deuterostome" - a broad biological category that encompasses a number of sub-groups, including the vertebrates.

If the conclusions of the study are correct, then Saccorhytus was the common ancestor of a huge range of species, and the earliest step yet discovered on the evolutionary path that eventually led to humans, hundreds of millions of years later.





"We think that as an early deuterostome this may represent the primitive beginnings of a very diverse range of species, including ourselves," added Mr Conway Morris.

"To the naked eye, the fossils we studied look like tiny black grains, but under the microscope the level of detail is jaw-dropping.

"All deuterostomes had a common ancestor, and we think that is what we are looking at here."

The study was carried out by an international team of academics, including researchers from the Cambridge University in the UK and Northwest University in Xi'an China.