“We’re here mainly by chance,” says Bertrand. “The asteroid could have missed Earth, it could have fallen in another area of the planet in the ocean and it would have made a difference in terms of which species were selected. The whole thing when I think about it – it’s crazy.”
Brusatte agrees. “It could have just whizzed right past, it could have just ruffled the upper layers of the atmosphere, it could have disintegrated as it got closer to Earth. It could have done anything, but just by dumb luck it made a beeline for the Earth.”
For the mammals alive today, perhaps it’s a good thing it did.
For many of these conditions, it is a two-way relationship. For instance, periodontitis may worsen conditions such as atherosclerosis, the hardening of the artery walls, and the presence of atherosclerosis also predisposes patients to periodontitis. There have been no randomised controlled trials (RCT), considered the gold standard of medical investigation, delving into this relationship (these would be hard to carry out ethically, denying one group treatment of their periodontitis for a prolonged period to see how it affected their atherosclerosis). However, periodontitis-causing bacteria usually found only in the mouth have been discovered embedded in atherosclerotic plaques.
Of all these chronic health conditions, diabetes has the strongest two-way link with periodontitis. People with type 2 diabetes have a three-fold greater risk of developing periodontitis than people without. For people who have type 2 diabetes and periodontitis, the infection worsens their body’s ability to control blood sugar levels.