The catastrophic cost of extended life-expectancy

More animals and birds are becoming endangered as humans live longer, scientists have warned.

Previously, deforestation, intensive farming and more tourists flocking to rare habitats had been blamed for the extinction of the some of the world's rarest animals.

But now scientists believe it could be humans ever-increasing lifespan - being described 'the determining factor' - that is having the largest impact on their survival. The study revealed that Australia, the U.S. Indonesia and the Philippines had among the highest numbers of endangered species.

Human life expectancy is rarely included among indexes that examine human impacts on the environment, but surfaced as the key predictor of global invasions and extinctions.

The study by the University of California, Davis, which is published in the Ecology and Society journal, found a strong correlation between the number of animals threatened with extinction and human life expectancies in 100 countries.

The factors considered included agricultural intensity, wilderness protection, altitude, undernourishment, tourism and life expectancy.

It found that New Zealand had the highest percentage of all endangered and invasive species combined, largely due to its lack of native terrestrial mammals.

African countries had the lowest percentage of invasive and endangered birds and mammals. These countries have had very little international trade, which limits opportunities for biological invasion.

The Philippines had the second highest proportion of endangered birds at 11 per cent, followed by the U.S. at nine per cent and Indonesia and Japan at seven per cent each.

Looking at the countries with the highest percentage of endangered mammals, Cuba came highest with 31 per cent, followed by the Dominican Republic with 29 per cent, Sri lanka with 26 per cent and India with 23 per cent.

Changes in biodiversity because of human actions have been more profound in the last 50 years than in the whole of prior recorded human history.

'Some studies have this view that there's wildlife and then there's us,' he said

'But we're part of the ecosystem. We need to start relating humans to the environment in our research and not leave them out of the equation. We need to realise we have a direct link to nature.'