Tian Tian, maybe definitely not

It is now virtually certain that Tian Tian, the female giant panda at Edinburgh Zoo, is no longer pregnant. Following artificial insemination in April, the zoo has been tracking Tian Tian’s hormone levels. The one to watch is progesterone. At around the time of ovulation, there is a small rise, with levels remaining roughly constant for several months. At this stage, the embryo is fertilized but is not developing. Then, some 60 to 100 days later, progesterone levels jump again from around 250 ng to 2500 ng (per gram of faeces) and the embryo begins to divide. In a press

Lonesome George and the late Lord Devon’s helmet

On Monday, when news of Lonesome George’s death began to reach editors around the world, I was asked to write his obituary for the Guardian. As I had already sent in one to Nature, they sensibly got the very excellent John Vidal to do it instead. John’s done a pretty good job and he generously cites my book Lonesome George: The Life and Loves of a Conservation Icon. I was, however, very puzzled to read that I’d reported that “George was irresistibly attracted to the late Lord Devon’s wartime helmet, presumably because it resembled the shell of a young tortoise.”

The death of Lonesome George

A team of vets, technicians and scientists has just carried out an autopsy on Lonesome George’s cold corpse. The early signs, according to a press release just issued by the Galapagos National Park, are that he suffered a cardiac arrest some time on Sunday morning. His posture suggests he was walking. I am guessing that the postmortem will not tell us much more about the cause of death. In all of the thousands of news stories that have covered Lonesome George’s passing, including in a short obituary I wrote for the Nature blog, you’ll read that George was thought to

The dance of the three-footed rhino

The rhinoceros stands on three legs. Her fourth – the front left – is shorter than the rest by an unlucky 13 cm and ends in a constricted knot of skin and bone. In a perfectly executed maneuver that incongruously brings a ballerina to mind, she shuffles her three good feet, as if on tip-toe, to a single point beneath her hefty frame. Her damaged limb begins to oscillate, looking more like a trunk as it swings backwards then forwards. Suddenly, and unexpectedly, she throws it upwards and her front limbs are cycling in the air. For a slow-motion instant,

Extinct Galapagos tortoise has just been hiding

A species of Galapagos tortoise – thought to be extinct for over 150 years – may, in fact, be alive and well. This finding – made by geneticists at Yale University– is particularly surprising when you consider that this reptile is of giant proportions, measuring more than a metre from the front to the back of its shell and weighing more than 200 kg. How could such a behemoth have gone unnoticed for so long? The answer, it turns out, is simple. They’ve been hiding. When Charles Darwin visited the Galapagos Island of Floreana in 1835, he found no sign