It is incredible, and it is incredibly hard to believe too, because although we've changed so much, we don't actually see any of those changes happening. Generation after generation, we just look the same. The problem is one of time. The periods over which even tiny changes happen are so long that almost beyond our imagination. But to make sense of those time periods, to see them in some perspective, I've brought you here to a cave deep in the French Pyrenees.

In the middle of the last century, a bookseller from a nearby town of Tuluz, used to visit this cave. And as a hobby, he dug around for bones and evidence of prehistoric remains. And he did this for some 40 years. And then late in the afternoon, on June the 11th, 1905, having been digging all day, he prepared to go but chose to go by a different route. And as he left, he was passing this wall and something caught his eye. He lifted up his lamp and this is what he saw--stencils of human hands from nearly 30,000 years ago. They are amongst the oldest images made by human beings on the planet. They are 6 times older than the Pyramids in Egypt and 8 times older than Stonehenge. Quite what they signified to the people who made them, no one knows. They were a Stone Age people and they came here at the coldest part of a last Ice Age. And over here are the most interesting images of all.

It is thought that these stencils here were made by someone no bigger than a toddler, a child in a primitive world, the son or daughter of somebody who you would think of as a caveman. And yet if I had taken such a child and brought it up as a baby in my own house, it would be indistinguishable from one of my own children.

Because by the time these people pressed their hands against these walls, all the changes which make us what we are had already happened. The evolution of the human body was, to all intents and purposes, complete. If this child were to be raised with my own children, it would look the same, it would talk the same, it would play the same computer games, and it would grow up wanting to be a doctor, a footballer, or maybe even an astronaut.

words and expressions

Pyrenees: 比利牛斯山脉：欧洲西南部山脉，从比斯开湾沿着法国与西班牙边境，到地中海在皮科·德·皮妮特，它高达3，406·2米(11，168英尺）

stencil:The lettering or design produced with such a sheet.
图案，文字：用模板或蜡纸复制出的字形或图案

toddler:One who toddles, especially a young child learning to walk.
蹒跚行走的人：一个蹒跚行走的人，尤指一个刚学习走路的幼儿

indistinguishable:（常与from连用）不能区别的；不能辨别的
"The synthetic material is indistinguishable from real silk, but much cheaper."
"这种合成衣料与真丝难以区别,但便宜得多。"

to all intents and purposes:实际上