The Hello, welcome to the naked scientists with me Chris Smith and also with

Ginny Smith. This week the world of parasites we find out what's living in you and on you, how these

invaders hijack your immune system and how they can even control the behavior of their hosts.

Plus in the news, the oldest remains of our first human ancestors are uncovered in Ethiopia.

Scientists weigh a stegosaurus, and NASA have the solar system's biggest asteroid, or should

that be dwarf planet in their sights and what

are they seeing the naked scientist podcast is powered by UKfast.co. UK.

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First up news that humans have been around longer than we realized.

Fossils of our genus, Homo, had previously only been found dating back to 2.4 million years ago.

Older fossils that have been found, like the famous female specimen Lucy, are from a more primitive lineage.

Now scientists working in Ethiopia have uncovered evidence suggesting the species that gave rise

to modern humans is older than we thought.

Bill Kimball is one of the team that made the discovery.

The specimen was found by an Ethiopian graduate student of ours, a man by the name of

Chalaccio Seumum in January of 2013 at a site known as Lady Gararo.

This is in the Ethiopian part of the East African Rift Valley.

He was part of a field survey project. They, as is commonly the case, identified a very specific area of exposed sedimentary rock to survey or explore one morning and focused on a hillside which was dotted

by freshly eroded bones. It's a very rich hillside. And Chilacho was walking up the slope of this hill, rather steep hill, and near the top he spotted just poking out of the loose eroded sediment a

pre-Molar tooth situated in a fragment of jaw that our team is attributing to one of the earliest known representatives of the genus Homo at about 2.8 million years ago.

How do you know how old that specimen is?

In eastern Africa, we're fortunate that the sites are in a rift valley setting.

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