Tag: humans and hominids

What is a species? | CNN

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A frog that looks like it’s made of tempered chocolate. A rainbow-colored fish that dwells in the ocean’s “twilight zone.” A hairy sloth with a coconut-shaped head.

These are just a few of the hundreds of newfound species that scientists described in 2022. The animals join a growing list of more than 1.25 million species that have been scientifically described and cataloged since the 18th century.

But what defines an organism as a species that’s new to science? And what exactly is a species, for that matter?

Biologists have wrestled with the concept for about as long as the field of biology has existed. Renowned naturalist Charles Darwin wrote in 1859: “No one definition has as yet satisfied all naturalists; yet every naturalist knows vaguely what he means when he speaks of a species.”

Fast-forward to the present, and the debate hasn’t changed much. “There are many definitions, and none of them applies broadly to all life on the planet,” said Bruno de Medeiros, assistant curator of insects at the Field Museum in Chicago.

And yet, recognizing and distinguishing between species is vital — and not only for biologists. It’s also necessary for cultivating the food we eat, treating diseases caused by different pathogens, and conserving endangered animals, plants and habitats.

The concept is also a critical part of understanding our own evolutionary history and defining our relationship to all life on the planet.

Teeming with life, Earth is covered with organisms of all shapes and sizes. Some are too small to see without a microscope. Others may tower hundreds of feet tall. Myriad life forms may gestate in a womb or sprout in soil, hatch from an egg or germinate in a corpse. They could be scaly, chitinous, furry or feathered; perhaps they are leafy, dotted with cilia or slick with slime. They might roam for thousands of miles or spend their lifetimes rooted in one spot.

Scientists make sense of all this biological diversity by classifying organisms based on shared ancestry and features such as physical appearance, internal structures and reproduction. A universal, hierarchical classification system was proposed in 1753 by Swedish biologist Carl Linnaeus, and it’s still generally followed today. This branch of science is known as taxonomy.

The broadest categories for all life on Earth are the domains. There are three domains — Bacteria, Archaea and Eukaryota — and they organize life based on cellular structure. Eukaryotes have cells that typically contain a single nucleus housing DNA: All multicellular life — animals, plants and fungi — as well as some types of unicellular life, are eukaryotes. Bacteria and Archaea are single-celled microorganisms that don’t have a nucleus, and they are evolutionarily distinct from one another.

The next category is kingdoms. In each kingdom, there are subcategories: phylum, class, order, family, genus and species. With each subcategory, the criteria for grouping organisms become progressively more specific and selective.

For example, humans are animals. That means we’re eukaryotes in the Animalia kingdom. Our phylum is Chordata, which includes any animal with a spinal cord. We are part of the class Mammalia. Within mammals, we are primates, sharing ancestry with apes, monkeys and lemurs. Our branch of the primate family tree is Hominidae, which includes our closest relatives: the great apes, such as gorillas, chimpanzees and bonobos.

Finally, we arrive at our genus and species — and our scientific name — Homo sapiens. We are the only surviving lineage in the Homo genus. Neanderthals (Homo neanderthalensis), our last remaining relatives in the Homo group, went extinct about 40,000 years ago.

Theoretically, “a species is a set of populations or one population of organisms that shares a common evolutionary history and reproduces with one another but not outside that group,” according to Nancy Simmons, curator-in-charge of mammalogy at the American Museum of Natural History in New York City.

If an animal population in a certain locale looks more or less the same, behaves the same, and mates and generates fertile offspring only with each other, “usually, we call this a species,” de Madeiros added.

But color, markings and even size can vary widely within a species; this is true for many species of spiders. Not all life reproduces sexually, so that criteria isn’t universal for defining a species, either. And in some organisms that sexually reproduce, closely related species may interbreed and produce fertile offspring. Coydogs, for example, are fertile hybrids of coyotes (Canis latrans) and dogs (Canis familiaris). Humans and Neanderthals interbred, and portions of Neanderthal DNA linger in the human genome, in people of non-African descent.

It can take millions of years for new species to evolve; often, what biologists are observing is evolution in progress. Closely related species can differ from each other a lot or a little — anatomically and genetically — depending on environmental circumstances and when they diverged from a shared ancestor.

In the best-case scenarios for describing new species, there are many data sources, Simmons explained. A candidate typically differs physically from its close relatives, with different measurements, different morphology (anatomical structures), or different colors or patterns.

“But then ideally we’d have other lines of evidence too — different genetic code or some sort of DNA variation,” Simmons told CNN. Behavior can also distinguish between species. In bats, for example, echolocation calls are often species-specific.

All these criteria — anatomy, genetics, behavior and location — enabled Simmons and her colleagues to describe a newfound orange-and-black bat species, Myotis nimbaensis, in 2021.

In recent decades, genetic data has transformed classification. Genomic analysis can reveal species-defining differences in near-identical organisms, as de Madeiros discovered while analyzing DNA sequences for palm flower weevils — a type of beetle with an elongated snout — that he had collected in Brazil in 2013 and 2014.

Initially, he thought there was a mistake in the data. “I had identical beetles that were clearly very distantly related species,” he said. But when he reexamined the insects, which belonged to the genus Anchylorhynchus, he noticed subtle differences in concave depressions in the males’ undersides. These indentations help the males fit snugly on top of females while mating, and likely are important for helping beetles identify and mate with females from the correct species, de Madeiros said.

In many ways, genetic data has made it easier for scientists to tell species apart — but it has also raised its own set of issues, particularly when closely related organisms that look alike and exhibit similar behavior are also very similar genetically.

“We get into questions of how much of a percentage of a difference in the genetic code do you have to have to be a distinct species — and people disagree on that, too,” Simmons said. “So, even when we have genetic data, you don’t find complete agreement about how to interpret it.”

However difficult it might be to define a species, scientists won’t be running out of new discoveries anytime soon. By some estimates, Earth is home to approximately 8.7 million species — about 6.5 million living on land and 2.2 million in the oceans, which means that roughly 86% of land species and 91% of marine species are yet to be found and described.

“We have a great challenge ahead to keep describing this diversity — how it evolves and how it will continue existing on our planet,” de Madeiros said.

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May 12, 2023
Unusual discoveries shake up what we know about ancient diets | CNN

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Buzz started to build about a decade ago around the meat-heavy paleo diet — an approach to eating that’s based on what our Stone Age relatives supposedly liked to consume.

But the truth is that we know relatively little about what our earliest ancestors ate, and what we’ve learned in recent years suggests that there was more than just mammoth steak on the menu.

Groundbreaking new discoveries, including some featured in this week’s CNN science newsletter, have revealed that the diets of early humans were surprisingly varied and that those ancient meals may have involved more sophisticated preparations than previously thought.

Neanderthals who lived 90,000 years ago in a seafront cave in what’s now Portugal regularly caught and ate crabs, roasting them on coals, according to a new study.

The finding is significant because it builds upon evidence challenging the long-standing notion that a taste for seafood — rich in omega-3 fatty acids that are important for brain growth — was one of the unique factors that made our own species, Homo sapiens, cognitively smarter than our extinct Neanderthal counterparts.

Meanwhile, in Kenya, another archaeological dig has revealed that early hominins feasted on hippo 2.9 million years ago, butchering the carcasses with the help of distinctive and unexpected implements.

The discovery may shed light on a key question in human evolution: Who first used stone tools?

In the HBO show “The Last of Us,” characters identify zombies among them by the fungi that burst from their bodies. Those fungal parasites manipulate their hosts to infect the communities around them, creating more monsters as a consequence. (HBO, like CNN, is a unit of Warner Bros. Discovery.)

In real life, the type of fungus that inspired the story, Ophiocordyceps, affects insects and does not cause problems for people.

However, the threat from fungal pathogens is increasing, experts say, and may grow much worse in a warmer, wetter and sicker world.

The climate crisis may also be contributing to the rise of drug-resistant superbugs, a new UN report has warned, with rising temperatures increasing the rate of bacterial growth and the rate of the spread of antibiotic-resistant genes between microorganisms.

Codebreakers have revealed the secrets within a lost trove of letters written by Mary, Queen of Scots, between 1578 and 1584 — during the 19-year period she was imprisoned by her cousin Queen Elizabeth I.

Written in cipher, the 57 letters from Mary Stuart to the French ambassador to England had been tucked away, wrongly labeled, in France’s national library.

The contents of the letters “will be a literary and historical sensation,” according to Dr. John Guy, a fellow in history at Clare College in Cambridge, England, and author of “Queen of Scots: The True Life of Mary Stuart.”

Just as impressive is how researchers deciphered the letters — the process involved computer algorithms, linguistic analysis and manual codebreaking techniques.

Geoscientists know little about the innermost reaches of our planet, but what happens deep beneath our feet is a source of fascination for many people. News last month that Earth’s inner core may have stopped turning was CNN’s most read science story in January.

Now, scientists have detected a previously unknown layer of partially molten rock 100 miles (161 kilometers) below Earth’s crust.

The revelation could help researchers learn more about the movements of the planet’s tectonic plates, which not only create mountains and earthquakes like this week’s devastating Turkey-Syria quake but also contributed to forming environments with the right chemical and physical conditions to support life in Earth’s earliest days.

Meanwhile, around 15 million people are at risk of experiencing “inland tsunamis,” according to a new report on glacial lakes.

Astronomers have spotted 12 previously unknown moons orbiting Jupiter, bringing its total number of confirmed moons to 92, the most of any planet in the solar system. The largest ones of the new batch will get names later this year.

The moons weren’t the only newly identified celestial bodies made public this week. An asteroid the size of Rome’s Colosseum photobombed an image taken by the James Webb Space Telescope, and astronomers found a dwarf planet with a ring that defies what’s known about celestial mechanics.

Also hanging out in the cosmic wilderness is a cherry red Tesla roadster launched into space five years ago by Elon Musk. To keep tabs on the sports car’s predicted location, NASA has an entry for the vehicle in the Horizons database for tracking space objects, but it’s difficult to say where the vehicle is with absolute certainty — or whether it’s still in one piece.

Check out these insightful stories:

— The first Black woman to join an International Space Station crew told CNN what inspired her to become an astronaut.

— How are scientists kept fed and happy in one of the most remote places on Earth? (Hint: It involves cheese.)

— See the snow leopard image that won in the wildlife photography awards.

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February 11, 2023
Neanderthals cooked meals with pulses 70,000 years ago | CNN

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Stone Age cooks were surprisingly sophisticated, combining an array of ingredients and using different techniques to prepare and flavor their meals, analysis of some the earliest charred food remains has suggested.

Plant material found at the Shanidar Cave in northern Iraq — which is famous for its burial of a Neanderthal surrounded by flowers — and Franchthi Cave in Greece revealed prehistoric cooking by Neanderthals and early modern humans was complex, involving several steps, and that the foods used were diverse, according to a new study published in the journal Antiquity.

Wild nuts, peas, vetch, a legume which had edible seed pods, and grasses were often combined with pulses like beans or lentils, the most commonly identified ingredient, and at times, wild mustard. To make the plants more palatable, pulses, which have a naturally bitter taste, were soaked, coarsely ground or pounded with stones to remove their husk.

At Shanidar Cave, the researchers studied plant remains from 70,000 years ago, when the space was inhabited by Neanderthals, an extinct species of human, and 40,000 years ago, when it was home to early modern humans (Homo sapiens).

The charred food remains from Franchthi Cave dated from 12,000 years ago, when it was also occupied by hunter-gatherer Homo sapiens.

Despite the distance in time and space, similar plants and cooking techniques were identified at both sites — possibly suggesting a shared culinary tradition, said the study’s lead author Dr. Ceren Kabukcu, an archaeobotanical scientist at the University of Liverpool in the United Kingdom.

Based on the food remains researchers analyzed, Neanderthals, the heavy-browed hominins who disappeared about 40,000 years ago, and Homo sapiens appeared to use similar ingredients and techniques, she added, although wild mustard was only found at Shanidar Cave dating back to when it was occupied by Homo sapiens.

A breadlike substance was found at the Greek cave, although it wasn’t clear what it was made from. The evidence that ancient humans pounded and soaked pulses at Shanidar Cave 70,000 years ago is the earliest direct evidence outside Africa of the processing of plants for food, according to Kabukcu.

Kabukcu said she was surprised to find that prehistoric people were combining plant ingredients in this way, an indication that flavor was clearly important. She had expected to find only starchy plants like roots and tubers, which on face value appear to be more nutritious and are easier to prepare.

Much research on prehistoric diets has focused on whether early humans were predominantly meat eaters, but Kabukcu said it was clear they weren’t just chomping on woolly mammoth steaks. Our ancient ancestors ate a varied diet depending on where they lived, and this likely included a wide range of plants.

Such creative cooking techniques were once thought to have emerged only with the shift from the hunter-gatherer lifestyle to humans’ focus on agriculture — known as the Neolithic transition — that took place between 6,000 to 10,000 years ago.

What’s more, she said, the research suggested life in the Stone Age was not just a brutal fight to survive, at least at these two sites, and that prehistoric humans selectively foraged a variety of different plants and understood their different flavor profiles.

John McNabb, a professor at the Centre for the Archaeology of Human Origins at the University of Southampton in the UK said that scientific understanding of the Neanderthal diet has changed significantly “as we move away from the idea of them just consuming huge quantities of hunted game meat.”

“More data is needed from Shanidar, but if these results are supported then Neanderthals were eating pulses and some species from the grass family that required careful preparation before consumption. Sophisticated techniques of food preparation had a much deeper history than previously thought,” McNabb, who wasn’t involved in the research, said via email.

“Even more intriguing is the possibility that they did not deliberately extract all the unpalatable toxins. Some were left in the food, as the presence of seed coatings suggests — that part of the seed where the bitterness is especially located. A Neanderthal flavor of choice.”

A separate study into prehistoric diets that also published Tuesday analyzed ancient humans’ oral microbiome — fungi, bacteria and viruses that reside in the mouth — by using ancient DNA from dental plaque.

Researchers led by Andrea Quagliariello, a postdoctoral research fellow in comparative biomedicine and food at the University of Padua in Italy, examined the oral microbiomes of 76 individuals who lived in prehistoric Italy over a period of 30,000 years, as well as microscopic food remains found in calcified plaque.

Quagliariello and his team were able to identify trends in diet and cooking techniques, such as the introduction of fermentation and milk, and a shift to a greater reliance on carbohydrates associated with an agriculture-based diet.

McNabb said it was impressive that researchers had been able chart changes over such a long period of time.

“What the study also does is support the growing idea that the Neolithic was not the sudden arrival of new subsistence practices and new cultures as it was once thought to be. It appears to be a slower transition,” McNabb, who wasn’t involved in the study, said via email.

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November 22, 2022