Three-dimensional scans of two mummified newborn woolly mammothsrecovered from the Siberian Arctic are revealing previously inaccessible details about the early development of prehistoric proboscideans. The research, conducted in part by American Museum of Natural History Richard Gilder Graduate School student Zachary T. Calamari, also suggest that both animals died from suffocation after inhaling mud. The findings were published July 8 in a special issue of the Journal of Paleontology.

“These two exquisitely preserved baby mammoths are like two snapshots in time,” said Calamari, who began investigating mammoths as an undergraduate at the University of Michigan working with paleontologist Daniel Fisher. “We can use them to understand how factors like location and age influenced the way mammoths grew into the huge adults that captivate us today.” 

Learn more. 

New Fossil Discovery Supports “Out of Africa” Monkey Dispersal Theory

New Fossil Discovery Supports “Out of Africa” Monkey Dispersal Theory

Just when and how Old World monkeys—a diverse and widespread group that includes macaques, baboons, and leaf monkeys—dispersed out of Africa and into Eurasia has never been fully understood. But a new discovery of a 7-million-year-old monkey fossil is providing important clues.

It was previously thought that at least some of these monkeys may have dispersed into Eurasia over the Mediterranean Basin or Straits of Gibraltar around 6 million years ago. At this time, the Mediterranean Sea dried up, allowing animals to cross between North Africa and Europe.

The newly discovered fossil, however, indicates that Old World monkey dispersal could have taken place through the Arabian Peninsula even before the Messinian Crisis. The fossil, a very small lower molar, was discovered on Abu Dhabi’s Shuwaihat Island in 2009. 

Read more on the Museum blog.

Why hot water freezes faster than cold water

Why hot water freezes faster than cold water

I found an interesting article online explaining why this phenomenon occurs.

Hot water seems to freeze faster than cold water, known as the Mpemba effect. The effect was named after the Tanzanian student who in 1963 noticed that hot ice cream mix freezes faster than a cold one. The effect was first observed by Aristotle in the 4th century BC, then later Francis Bacon and René Descartes. Mpemba published a paper on his findings in 1969.

Theories for the Mpemba effect have included: faster evaporation of hot water, therefore reducing the volume left to freeze; formation of a frost layer on cold water, insulating it; and different concentrations of solutes such as carbon dioxide, which is driven off when the water is heated. Unfortunately the effect doesn’t always appear - cold water often does actually freeze faster than hot, as you would expect. But this Mpemba effect occurs regularly, and no one has ever been able to definitively answer why.

Now a team of physicists from the Nanyang Technological University in Singapore, led by Xi Zhang, have found evidence that it is the chemical bonds that hold water together that provide the effect. Each water molecule is composed of one oxygen atom bonded covalently to two hydrogen molecules. These bonds involve atoms sharing electrons and are well understood. The separate water molecules are also bound together by weaker forces generated by hydrogen bonds. These forces occur when a hydrogen atom from one molecule of water sits close to an oxygen atom from another.

The team now suggest it is these bonds that cause the Mpemba effect. They propose that when the water molecules are brought into close contact, a natural repulsion between the molecules causes the covalent bonds to stretch and store energy. When the liquid warms up, the hydrogen bonds stretch as the water gets less dense and the molecules move further apart. 

The stretching in the hydrogen bonds allows the covalent bonds to relax and shrink somewhat, which causes them to give up their energy. The process of covalent bonds giving up their energy is essentially the same as cooling, and so warm water should in theory cool faster than cold. The team’s calculations suggest that the magnitude of the covalent bond relaxation accounts for the experimental differences in the time it takes for hot and cold water to freeze.