2 . It is sometimes thought that the longing for material goods, the need to buy things, is a relatively modern invention.     1     Trade or shopping is certainly an ancient desire, and existed before our ancestors invented writing, laws, cities or farming, even before they used metal to make tools.

Humans are born to trade.     2     Evidence from hunter-gatherers suggests that the exchange of food and other necessary things comes naturally, as well as the ability to keep a record of the credits involved. And once trade begins, the benefits are hard to resist.

Ancient local coastal people in northern Australia traded fish hooks, along a chain of trading partners, with people living 400 miles inland, who cut and polished local stone to make axes (斧子).     3     Finally, both groups of “producers”, by concentrating on things they could produce and exchanging them for other things they needed, benefited as a result.

Trade in the necessities of life, such as food and simple tools, is not really surprising, considering the link between these basic items and survival. What is surprising, though, is that our taste for unnecessary expensive objects also goes back a long way.

In South Africa, 100,000-year-old decorative dyes (染料) have been found in an area where none were produced.     4     Small round pieces of glass 76,000 years old were also found at the same place. The earliest jewellery known to us were not just random findings — they were grouped together in size and had holes like those used for threading onto a necklace.

Archaeologists argue that trade prepared the way for the complex societies in which we live today.     5     However, their modern equivalents — fast cars and expensive clothes — hold the same attraction for us as “trade goods” did for people 100,000 years ago.