September 30, 2019

Last month, in late August, scientists published a description of a 3.8-million-year-old fossil skull, allowing people to gaze into the face of perhaps our earliest ancestor, Australopithecus anamensis. According to one researcher, the remarkable fossil is the most complete skull of the “oldest-known species” of the human evolutionary tree. The important fossil helps define the ancient human evolutionary family, but it also brings more questions to the often cloudy relationships among that family’s members.

Paleontologists discovered the near-complete skull of Australopithecus anamensis in Ethiopia in 2016. Credit: © Dale Omori, Cleveland Museum of Natural History

A. anamensis belongs to the hominin group of living things that includes human beings and early humanlike ancestors. A team of paleontologists led by Yohannes Haile-Selassie from the Cleveland Museum of Natural History found the hominin skull in 2016 at a site called Woranso-Mille in the Afar region of Ethiopia. The fossil, officially known as MRD-VP-1/1 (MRD for short), was discovered in two halves that fit together, making up a nearly complete skull. The skull’s position in volcanic sediments enabled scientists to determine its age—3.8 million years—with great precision. The anatomical features of the skull helped identify it as A. anamensis, one of the earliest known hominin species. This species was first identified from a handful of fossil skull fragments and other bones discovered at Lake Turkana in northern Kenya in the 1990’s. Those specimens are between 4.2 million and 3.9 million years old.

Scientists used the fossilized Australopithecus anamensis skull to create this image of one of humankind’s earliest ancestors. Credit: © John Gurche/Matt Crow, Cleveland Museum of Natural History

The MRD skull shows that A. anamensis had a small brain, a bit smaller than that of a modern chimpanzee. The skull more closely resembles an ape than a modern human, with a large jaw and prominent cheekbones, but the canine teeth are much smaller and more humanlike. And, like humans, A. anamensis walked upright on two legs. Sediments and other fossils show that the region where the skull was found was arid, but the ancient creature died in a vegetated area near a small stream that entered a lake.

The site in Ethiopia where MRD was discovered is not far from the village of Hadar, where fossils of another early hominin, Australopithecus afarensis, were first discovered in 1974. A. afarensis is known mainly from the partial skeleton of an adult female, the famous “Lucy,” found in deposits dating to about 3.2 million years ago. Other A. afarensis fossils date to nearly 3.8 million years ago, which suggests Lucy and her kind may have coexisted with A. anamensis.

Most scientists, however, think that Lucy and her kind evolved from A. anamensis, and that the transition occurred as one species disappeared and the other took over. Scientists now understand that A. anamensis could still be ancestral to Lucy, but that other A. anamensis populations continued to thrive unchanged as her neighbors. The prehistoric landscape of East Africa had many hills, steep valleys, volcanoes, lava flows, and rifts that could easily have isolated populations over many generations. Over time, the populations eventually diverged. Scientists think that one of these species eventually gave rise to Homo, the human genus.

July 7, 2017

A new study of ancient cat DNA reveals what many cat owners might long have suspected: your pet is barely domesticated at all. A team of scientists analyzed genetic material from more than 200 ancient cats obtained from Viking graves, Egyptian mummies, and Neolithic (later Stone Age) sites. The study revealed that despite having lived alongside people for thousands of years, cats really began to change only quite recently. The study was published in June in the journal Nature Ecology and Evolution.

A recent study showed that domestic cats like this Maine coon remain genetically quite similar to their wild ancestors. Maine coons, developed in New England in the 1800′s, are the largest domestic cat breed. Credit: © Linn Currie, Shutterstock

Cats have a long association with people. Archaeologists discovered a cat buried alongside a human in a 9,500-year-old grave in Cyprus. Yet cats have not not been fully domesticated the same way that dogs, cattle, pigs, sheep, or goats have been. Those familiar pet and farm animals differ from their wild ancestors in anatomy, behavior, and genetics. Modern house cats, however, remain very similar to their wild ancestors. Pet cats, of course, are much smaller than their wild cousins, but they remain near anatomic mirrors. Behaviorally, watch a panther or a lion in a nature program or in a zoo—then a house cat stalking a bird or simply watching you walk across the room—and you might notice quite similar patterns: sleeping a lot, playing, grooming, investigating, hunting, and even jumping into empty boxes. And genetically speaking, despite thousands of years of human interaction, pet cats did not begin to change until the past few centuries—and then, only a little. The domestication of cats has been neither complete nor easy. In fact, all house cats are descended from just one presumably friendlier-than-the-rest ancestor: the African wildcat.

The wildcat, from which modern house cats descended, still roams Africa, Asia, and Europe. Look familiar? Credit: © Vova Pomortzeff, Shutterstock

The genetic study focused on cat mitochondrial DNA (mtDNA), which is inherited unchanged solely from the mother. This fact makes mtDNA especially useful to trace the ancestry of different animal species. The genetic evidence showed that cat domestication probably began about 9,000 years ago in the Middle East, where farming started. Scholars think that wild cats (wildcats among them) were initially attracted to rodents that infested grain stores of early farmers. With plenty to eat, the cats stuck around the farms but never became fully domesticated. Cats then followed farming peoples as they migrated into Europe more than 6,000 years ago.

The genetic study showed that the familiar tabby markings of modern cats developed during the Middle Ages. Credit: © Shutterstock

The recent study found, however, that most modern pet cats are not directly descended from these first domesticated felines. More than 3,000 years ago, a second episode of cat domestication happened in ancient Egypt. These cats spread out of Egypt to Europe and beyond along Greek and Roman trade routes as far north as Scandinavia and into Asia. Most modern pet cats are descended from this second migration group.

The mtDNA analysis revealed that most domestic cats over the past 9,000 years were striped, like their wild ancestors (witness the tiger). The familiar tabby coats—symmetrically patterned with light stripes and blotches of a dark and light colors—of many house cats today were uncommon until the Middle Ages. It was around that time that people started paying more attention to their cats and started breeding them for different appearances and purposes. The genetic evidence even pinpointed the tabby mutation to western Turkey in the 1300’s. Most cats today carry this tabby gene, but there are now many different breeds from all over the world. The vast majority of cat breeds have been created since the early 1900’s.

Cat shows are popular today, but the very first cat show was much earlier than you might think. According to most accounts, the first show took place in 1598 at St. Giles Fair in Winchester, England. The first modern cat show was held at London’s Crystal Palace in 1871.

March 10, 2017

Hard gunk stuck in the teeth of fossil Neandertal jaws shows that the prehistoric human beings had a widely varied diet and a sophisticated knowledge of medicinal plants. Scientists analyzing dental calculus (a hard, yellowish substance formed by the buildup of plaque between teeth) from three Neandertal fossils found dramatic differences in diet and evidence that Neandertals likely used some foods as medicine. The scientists’ findings were published in the March 8 issue of the journal Nature.

The teeth of this fossilized Neandertal jaw revealed traces of poplar bark, a source of aspirin. The individual had also consumed Penicillium mold, source of the natural antibiotic penicillin. Credit: © Paleoanthropology Group MNCN-CSIC

Neandertals were prehistoric human beings who lived in Europe and central Asia from about 150,000 to 39,000 years ago. They looked quite different from modern humans. Neandertal skulls were huge compared to ours, with a projecting face; no chin; a low, sloping forehead; and a thick browridge (raised strip of bone across the lower forehead). Because Neandertals had such a brutish appearance, people long assumed the these prehistoric humans possessed only a crude and simple culture. However, new evidence shows they were perhaps smarter than we previously thought.

An international team of scientists examined three fossil Neandertal skulls dating from 42,000 to 50,000 years ago. Two of the skulls were from El Sidrón, a cave in Spain, and one was from Spy Cave in Belgium. The teeth of these fossils were coated with thick layers of hardened dental calculus. The scientists knew that this material preserves DNA from microbes and food debris that pass through an individual’s mouth during their lifetime. The dental calculus of the Spy Neandertal contained traces of meat from wooly rhinoceros and wild sheep, while evidence of plant foods was largely absent. In contrast, the two Spanish Neandertal fossils appeared to have survived on a vegetarian diet of edible moss, mushrooms, tree bark, and pine nuts.

Neandertals lived in Europe and Central Asia from about 150,000 to 39,000 years ago. Credit: © Jay H. Matternes

Other evidence showed that the El Sidrón Neandertals probably also used plants for medicine. The scientists recovered DNA from poplar trees in the dental calculus. While not eaten for food, these trees contain salicylic acid, the pain-relieving ingredient in aspirin. Preserved spores of the Penicillium mold, from which the life-saving antibiotic penicillin is produced, were also recovered. The scientists think the Neandertals ate the plant sources for their medicinal properties. One fossil skull showed evidence of a painful tooth infection, and DNA from a microbe known to cause stomach problems was also recovered from the calculus. Aspirin and penicillin would have helped.

Neandertals died out about 39,000 years ago, when physically modern human beings migrated into Europe. However, Neandertals did not disappear completely. Genetic evidence shows at least some Neandertals interbred with modern-looking populations that settled Europe, Asia, and the Pacific Islands. Neandertals are extinct, but they remain part of the ancestry of some modern peoples today.