[quote][url=http://www.nature.com/nature/journal/v471/n7336/full/nature09678.html]Palaeontologists characterize mass extinctions as times when the Earth loses more than three-quarters of its species in a geologically short interval, as has happened only five times in the past 540 million years or so. Biologists now suggest that a sixth mass extinction may be under way, given the known species losses over the past few centuries and millennia. Here we review how differences between fossil and modern data and the addition of recently available palaeontological information influence our understanding of the current extinction crisis. Our results confirm that current extinction rates are higher than would be expected from the fossil record, highlighting the need for effective conservation measures.[/url] [/quote] [quote][url=http://news.bbc.co.uk/1/hi/sci/tech/2000325.stm]It's possible that 4,000 species of mammals within a few decades.]Almost a quarter of the world's mammals face extinction within 30 years, according to a United Nations report on the state of the global environment. Factors leading to mammals' extinction continue with "ever increasing intensity" The destruction of habitats and the introduction of alien species from one part of the world to another are blamed for the threatened loss to biodiversity.[/url] [/quote] It's also suspected we could lose [url=http://www.thetimes.co.uk/tto/news/world/article3868636.ece]rhinos,[/url] [url=http://theweek.com/article/index/248599/]elephants[/url] and [url=http://news.bbc.co.uk/1/hi/sci/tech/3119434.stm]lions.[/url] Thoughts? And yes, [url=http://books.google.co.uk/books?id=mbU-F42JU1AC&lpg=PA129&ots=jC21hu-avG&dq=humans%20responsible%20for%20holocene%20extinction&pg=PA129#v=onepage&q=humans%20responsible%20for%20holocene%20extinction&f=false]we're probably responsible.[/url]