The earliest traces of animal life on earth.

Do rocks found in Canada show animal life 350 million years older than any found before? And, delving to the core of Mars, the guts of cats, and into the life of Steven Weinberg.

Prof Elizabeth Turner of Canada's Laurentian University reports in the journal Nature structures in some of the oldest sedimentary rocks that resemble the residue left by sponges such as the sort you might find in a bath. 350 million years older than the oldest such fossils yet identified, if they are left by such animals, they represent a complex life that existed some 90 million years before - it has been supposed - there was even enough oxygen to support such development. As she tells us, rather like previous geologists investigating the deep history of life, Elizabeth has been sitting on this idea since she was a young researcher.

Since 2019 NASA's InSight probe has been on the surface of Mars listening for seismic waves from below to try to form a picture of the planet's internal structure. Last week in the journal Science, three papers presented data and analysis and some surprises for planetary scientists trying to work out how a planet that began almost, but not quite, so similar to earth could have turned out so different today. Cambridge University's Dr Sanna Cottaar gives us her take on the exciting findings.

Most of our understanding of genetics – diseases and heritability – is derived from decades of deep studies into just a few model species besides humans. But Prof Lesley Lyons runs a lab at the University of Missouri focusing almost entirely on cats. She describes to Roland a proclamation she makes this week to her fellow scientists to do more work into cat genetics and how, because of the similarities between cats and human genomes, that will bring all sorts of benefits to human (and cat) health.

Earlier this week we heard of the death of physicist Steven Weinberg - one of the giants of 20th century particle physics and cosmology. Roland presents recordings and reminiscences of a remarkable scientist who provided so much insight into the first 3 minutes of our universe's existence...

Image: Field locations in Northwest Territories, Canada Credit: Elizabeth Turner, Laurentian University

Presenter: Roland Pease Producer: Alex Mansfield