generation

"This approach to learning contributes to what we call 'cumulative culture' -- the ability to build on existing knowledge and pass it down through generations," Hewlett said.

The population of the white-backed vulture, for example, declined by around 90 percent in just three generations -- equivalent to an average decline of 4 percent per year.

In addition, the older generation increased by about 42,500 people, accounting for 37.1% of the total population.

However, pedigrees are recorded manually, and they may go back only a few generations.

He added that benefit rises linked to having children had gone up by less than pension payments, adding: "Inequality is generational, and the generation that experiences it the most are the young".