Category: science

In the 1300s, the Black Plague swept through Europe. To create a “family tree” of the plague, scientists conducted a genetic analysis of Yersinia pestis strains taken from 34 individuals who died in 10 different countries between 1300 and 1700.

The results suggest that over time, the bacteria Yersinia pestis mutated and diversified into multiple clades. All the clades
found in the study were related to back to one ancestral strain.  That suggests that the Black Plague entered Europe just once. And the oldest strain, the one that appeared to have been the others’ ancestor, was from remains found in a little Russian town named Laishevo.

Here’s where a caution must be added. Such analyses are always limited by the available bacteria strains – the family tree will be added to over time as more bodies are recovered and more bacteria strains isolated.

Forty years ago, a Buddhist monk found a human mandible bone at Baishiya Karst Cave, perched 10,000 feet above sea level on the Tibetan Plateau. The bone they found has now been dated to 160,000 years ago. And analysis of the proteins caught in its teeth demonstrate that the mandible belonged to the Denisovan branch of the hominin family.

This is the first evidence for Denisovans found outside of southern Siberia’s Denisova Cave. That cave is just 2,300 feet above sea level. It is also about 1,750 miles northwest of Baishiya Karst Cave. The mandible therefore revealed the Denisovans were widely distributed, and able to adapt to extremely high altitudes.

This is likely related to the mutation, found in previous Denisovan genetic studies, that assists survival in low-oxygen environments such as the high-altitude Tibetan Plateau. The same mutation has been found in present-day Tibetans. And given that the Denisovans once lived in the area, perhaps a long-ago intermarriage introduced the gene to the Tibetans? It seems more likely than the exact same gene randomly mutating twice.

The 145 million years is a little arbitrary, but it makes for a fun and unusual way to look at the world. Are your mountains young or old?

Symptoms of atherosclerosis, or hardening and narrowing of the arteries, have been detected in the mummified remains of four Inuit adults who lived in Greenland about 500 years ago. The recent study used computerized tomography to examine the bodies of the two men, who are thought to have been between 18 and 22 and 25 and 30 at the time of death, and two women, who died sometime between the ages of 16 and 18 and 25 and 30, and one infant. Three of the four adults showed evidence of arterial calcification. Increased gunk in arteries can lead to life-threatening conditions such as strokes and heart attacks.

These Inuit’s atherosclerosis is a surprising find because current health theories suggest that a diet rich in marine foods and omega-3 fatty acids, such as that eaten by preindustrial-era Inuit peoples, would offer protection from arterial calcification. The individuals’ entire circulatory systems were not preserved, however, so the researchers were not able to determine the full extent of the damage to their arteries. The scientists also noted that heavy exposure to smoke from indoor fires may have outweighed the heart-health benefits of an active lifestyle and fatty-fish-based diet.

Trinity College, one of Cambridge University’s colleges, has more Nobel laureates than most countries! It has 34 Nobel laureates. Only four countries (the USA, France, Germany, and the UK excluding Trinity College) have more.

By the way, of those 34 laureates, none are women.

Coral reefs have existed for over 400 million years!

It is known that animal herding, which had been in northeastern Africa since about 8,000 years ago, made it to southern Africa by about 2,000 years ago. But it has been an open question whether the pastoral life was brought south by immigrants, or whether it was adopted by hunter-gatherers already in the area.

A multinational team of scientists recently examined 41 genomes from individuals who lived in Africa between 4,000 and 300 years ago. The genomes suggested that pastoralists migrated from southwestern Asia into eastern Africa around 5,000 years ago. They interbred with local foragers, mixing genomes.

However, about 3,300 years ago, the inbreeding ceased. Pastoralism had already been established by this point. The immigrants were now locals. So this study creates a new question: why did the genomes separate? What happened that pastoralists and hunter-gatherers suddenly stop intermarrying?

Recent work on the mummies of working people at Deir El-Medina in Egypt suggest that tattoos were much more common than previously thought 3,000 years ago. In the local cemetery, seven mummified women have been identified with tattoos. One had over 30!

The subject of the tattoos included sacred motifs such as Wadjet eyes, baboons, cobras, cows, scarab beetles, and lotus flowers. Some tattoos appear to have religious meaning, while others appear to offer healing or protection. Just like today, ancient Egyptians got tattoos for many reasons.

Yemen has a famously isolated island, Socotra, whose separation from the mainland and varied climate features resulted in the development of many unique flora and fauna. A 1990 biodiversity study found that there are 700 species on Socotra that live nowhere else on earth. And an estimated one-third of its species are unique to the island.

But did you know that Socotra has been occupied by humans for the past 2,000 years? The result is the degradation of its famous biodiversity: the island once featured wetlands and pastures that were home to crocodiles, giant lizards, and water buffaloes. Their homelands have been replaced by sand gullies and the animals who once called the wetlands home have disappeared.

The remaining Socotra fauna are those which can survive in the drier climates. And they are greatly threatened by goats and other introduced species. Many native plants only survive where there is greater moisture or protection from livestock, meaning that continuous human effort is needed to preserve them.

The Maya at Chichen Itza were known to practice human sacrifice a thousand years ago. Who they were sacrificing, though, has long been a mystery. A recent isotope analysis of tooth enamel from sacrificial victims
thrown into the city’s Sacred Cenote shows that there was some variety in who was sacrificed. Some  grew up locally, while others hailed from the Gulf Coast, the
Central Highlands, and as far away as Central America.

How the mix of individuals were chosen, and how those from further away ended up in Chichen Itza, remains unknown – there is always something more to investigate.