The lungs of birds move air in only one direction during both inspiration and expiration through a set of tubular gas-exchanging bronchi called parabronchi. On the other hand, in the lungs of mammals and other vertebrates, air moves tidally into and out of terminal gas-exchange structures, called alveoli (Figure 1). The work carried out by […]
You’re sitting in a room with an all-southern view. Suddenly, a bear walks by the window. What color is the bear? Young Sherlock Holmes. Barry Levinson (1985) The polar bear (Ursus maritimus) is one of the most unmistakable mammals of the planet. Its white fur is maybe the most straightforward reason for this distinctiveness, but […]
Alfred Russel Wallace (1823-1813) is especially known as one of the discoverers of evolution by natural selection. However, among his various contributions to the development of modern biology we can also consider the British naturalist as the father of biogeography: the study of the spatial distribution of organisms over the surface of the planet. Wallace’s […]
It is interesting how some ideas get stuck in our minds even long after it is proved that they are incorrect or incomplete. Haeckel’s Recapitulation Theory, which states that during the embryological development of an organism it undergoes through different stages recalling the evolutionary history of its ancestors (ontogeny recapitulates phylogeny), is considered obsolete nowadays […]
Life is full of compromises, and so is evolution. We often wonder about the explanation for particular traits that we find in many different organisms; distinct characteristics present in some of those organisms but not in others. We may hypothesize their story, and it can make sense, but finding actual evidence to support it will […]
It took a multi-million-dollar collaborationship between Discovery Channel and NHK to obtain the first images of a giant squid in its native environment. The broadcasters announced this month that they finally succeeded on filming a relatively small specimen of Architeuthis dux at a depth of 630m in the northern Pacific Ocean. But what makes this […]
From the genetic point of view, when should a man be more interested in caring for his sister’s children than his wife’s? A quantitative analysis of Alan Rogers, University of Utah, shows that this behaviour should be the choice in populations where adultery is common or permitted. In the animal world, males caring for offspring […]
Nowadays, central Australia is mostly a huge desert. It was not always like that: only five million years ago, this area had a completely different look, with humid forests, rivers, streams and lakes, a strong contrast to the current dry landscape. A significant portion of the Australian desert is, actually, full of water. Water that […]