The truth about cats: Left paw = right-brain male / Right paw = left-brain female.

January 27, 2018

The late-night comedian and Daily Show host Jon Stewart used to a bit called, “According to a new study…” as a way to draw attention to TV newscasts that over-rely on studies to provide news content and fill air time.

The media world — and the animal kingdom in general —

has been tossed upside down in the past week by a new study that claims cats are right-pawed or left-pawed, depending on which front paw they use first to reach out or swat something with.

According to this study, published in the January issue of the journal Animal Behaviour (Est. 1953), right-handedness and left-handedness in cats is determined by gender: Male cats tend to favour their left paw; females tend to favour their right.

One can be forgiven for taking the study with a grain of salt, or catnip if you prefer, because we’re living in the era of Fake News, aka #fakenews — and because, as Stewart reminded us on an almost nightly basis on his Daily Show, the media like nothing more than a new study that tells us something we didn’t know, and has broad audience appeal besides.

This particular study, as reported by National Public Radio (NPR) in the United States, and many, many other media outlets, including Smithsonian magazine, The Guardian and LiveScience.com, to name just a few, was conducted by a trio of psychology-department researchers at the Animal Behaviour Centre at Queen’s University in Belfast, Northern Ireland.

The study involved 44 cats in all — 24 male, 20 female, all neutered or spayed, of mixed breeds, between the ages of one and 17 years.

Cat owners were asked to monitor their cats’ daily routine, focusing on spontaneous behaviour such as what paw they used to reach for food, step into their litter tray, or climb up and down a flight of stairs. Cat owners were also asked to monitor whether their cat preferred to rest or sleep on which side. Survey participants — the humans, not the cats — were asked to monitor their cat’s behaviour every day until 50 responses were reached for each question.

The study is not entirely new. Behavioural psychologists at the same university conducted a similar study in 2010, as reported at the time in Pets Magazine and other places.

That study found that, as with human left- or right-handedness, cats do tend to favour one paw over the other. The results then were similar to the results now. The 2010 researchers found that most cats will use either paw for simple things. When faced with a more complex task that requires dexterity, female cats will favour their right paw while male cats will favour their left.

Fake news? Or yet another case of cats being, well, cats? It could well take a cat psychologist to suss out the difference.

In the 2010 study, as reported at the time in the Daily Telegraph, “in one particularly difficult task – fishing a piece of tuna out of a small jar – all 21 females used their right paw.”

Twenty of the 21 tom cats studied used their left, while one of the males was judged to be ambidextrous.

In simpler games, such as grabbing a toy mouse and dragging it along on a string, cats showed equal preference for either paw.

The researchers likened the pattern to the way we humans use either hand for a simple task, such as opening a door, but favour one hand over the other for writing.

“The more complex and challenging (the task), the more likely we’re going to see true handedness,” study leader Dr Deborah Wells told New Scientist magazine at the time.

Though the idea of testing right-handedness against left in house-cats sounds like the classic definition — where there is any definition at all — of fake news, there is a scientific question that goes beyond finicky couch moggies.

Studies of chimpanzees in the wild have shown that individual chimpanzees show a distinct preference for one hand over the other when using tools.

Hand-preference in primates is complicated, and not always easy to judge. There are still a lot of unanswered questions. Among humans, for example, left-handedness is more common among men than women, but no one can explain why.

©Queen's University Belfast/Dr. Deborah Wells

“Further work is needed to investigate this,” study co-author Wells told NPR earlier this week. “The strong (gender) effects reported here . . . point more and more strongly to underlying differences in the neural architecture of male and female animals.”

Aside from the curiosity factor, why does any of this matter?

Left-limbed animals, Wells told NPR, rely more heavily on the right hemisphere of their brains, and tend to display more aggression and a more pronounced reaction to fear than right-limbed animals, which tend to use the left hemisphere of their brains more.

I can personally attest to one of the results of the study: My own couch moggy, a female, favours her right paw over her left — and I have the scars to prove it.

Most detailed look yet at how early humans left Africa.

August 07, 2017

“The more we understand about this particular event in human history, the more it provides a complete picture of our past,” University of Washington evolutionary biologist Joshua Akey told New Scientist recently.

“This particular event in human history” is the early migration of humankind from the so-called Dark Continent to Mesopotamia, the Middle East and beyond, into Europe and, eventually, North America and the equatorial Pacific.

As much as is known about these early migrations — and we know a lot — much remains a mystery. This has been an active and unpredictable period for new discoveries about early humankind, from fossil evidence in regions as far-flung as the Rif mountains of Morocco to the Australian Outback. Incredibly, new cave art is still being discovered in areas of Europe that have been settled for millennia. Carbon dating continues to prove the old adage that the more we learn, the more we learn that we don’t know.

Modern humans emerged out of Africa — that much is reasonably certain — but exactly when, and how, remains the subject of fierce debate.

Two theories have jumped to the fore, emphasis on the word “theory.” One posits that our earliest ancestors left Africa in a single wave, around 40,000 to 60,000 years ago. Many of these groups died out, though, even as a handful passed their DNA to their descendants as they settled the break basket of the Tigris and Euphrates river valleys.

A new theory, which has gained traction of late, is that early humans migrated in several waves, not just one, and that the waves originated thousands of years earlier than was previously believed.

The answer, many scientists now believe, lies buried in our human genome. The authors of no fewer than three recent studies have analyzed the genomes of roughly 800 individuals from 250 populations scattered throughout the globe. In one study, Harvard geneticist David Reich argues that the clear genetic similarities between remote communities far removed from one another suggests that modern humans did indeed emerge in a single wave from Africa, even though DNA evidence shows that our earliest African ancestors were already dividing into separate groups more than 200,000 years ago — a full 120,000 years before that early migration, if the genetic findings are to be believed.

Early human development shows that rapid advances in technology, culture, art, language, religious rites and the use of tools occurred during a relatively short span of time, between 50,000 and 80,000 years ago — in other words, around the same time as those early migrations out of Africa.

In an early sign of how climate change affected human migrations, scientists now believe that fluctuating temperatures and an increasingly unpredictable life cycle of plant growth hastened the urge to move, even as the natural barrier ofmountains and deserts kept groups of people separate, leading to genetic differences in human populations around the world.

Separate genetics studies from Harvard, the University of Washington and the Estonian Biocentre in Tartu, Estonia suggest that while most modern non-Africans are indeed descended from a single, out-of-Africa exodus roughly 80,000 years ago, genome studies in Papua, New Guinea suggest there may have been an earlier exodus, according to Cambridge-educated molecular biologist Luca Pagani, senior researcher with the Estonian Biocentre in Tartu, Estonia.

Another recent study, this one supervised by evolutionary geneticist Eske Willerslev at Denmark’s University of Copenhagen, has found that indigenous groups in Australia are strikingly distinct, genetically speaking, from other groups in Australia, despite sharing the common gene that suggests they were all descended from a single, founding wave of early human migrations from Africa.

©Eske Willerslev/University of Copenhagen

Why do we care? Why do we continue to care?

“People are just inherently interested in their past,” Akey told New Scientist, whether they’re from Seattle or South Yunderup township in Western Australia.

Answers inevitably lead to new questions, even as missing pieces in the puzzle are found. The mystery of early humankind — who we are, where we came from — continues to be one of the most fascinating riddles facing humankind today.

Out of Africa: plot thickens in story of early human migrations.

April 12, 2017

Everybody loves a good story. Even the best stories, though, can change in the telling.
Palaeontologists have argued for years — decades, in fact — that modern humans first emerged in Africa 200,000 years ago and migrated around the world some 50,000 to 100,000 years ago.
Exactly what route they took, though, where they left and where they arrived, is still the subject of much scientific conjecture and debate.
Now a recent study co-authored by the Department of Genetics at Harvard University Medical School in Cambridge, Mass. has brought scientists closer to understanding some of the finer details.

Humankind’s story begins in Africa with a group of hunter-gatherers, no more than a few hundred in all, who set out toward the distant horizon, for reasons known only to them. Today, 100, 000 years later, seven and a half billion of their descendants are spread throughout the Earth, “living in peace or at war,” as National Geographic geneticist Jamie Shreeve put it in a 2006 story for the magazine, “believing in a thousand different deities or none at all . . . faces aglow in the light of campfires and computer screens.”
The unanswered questions, shaped in the silence of prehistory, include: Who were these first modern humans in Africa? What compelled a small band of their descendants to leave the safety and security of the home they knew to set out for the unknown of Eurasia? Did they mix and intermarry other, earlier members of the human family tree along the way? When and how did early humans first reach the Americas?

The Harvard study, reported earlier this year in New Scientist, traced early human migrations by contrasting and comparing previously existing studies of ‘out of Africa’ routes with new DNA techniques that continue to improve the way scientists identify and sequence genomes of our early ancestors. The secret, the scientists say, is to find more efficient ways to analyze and understand the data, and improve our understanding of human migrations.
It’s a work in progress, the paper’s lead author, Dr. Mark Lipson, stressed. There are no easy answers. The secrets of those early human migrations remain just that.
Still, over time, more blanks on the giant, blank canvas of human prehistory are being filled in with each passing day. Incomplete maps are always subject to interpretation. “Here there be dragons,” inscribed on an old map, is always assumed to be true — or possible — until someone proves it isn’t. The slow, painstaking work of scientific discovery is often just as much about proving a negative as it is proving a positive. (Pedants, as typified by The Atlantic’s Robinson Meyer in a 2013 article, will point out that no old map, at least no early-modern European map, actually featured the inscription, Here there be dragons, but why spoil the beauty of a thing with an unprovable? All that means is that if there is a map with the words Here there be dragons or its Latin equivalent, Hic sunt dracones, inscribed on it, it hasn’t been found yet.)

Taking into consideration the possibility — likelihood, even — that early hominids interbred with other hominid species along the way, the Harvard study found that there was a definitive split between eastern and western populations once modern humans left Africa. This split happened as recently as 45,000 years ago, and explains how the early aboriginal inhabitants of Australia and New Guinea diverged genetically from their more northern cousins. Interestingly, unlike the closely studied migration of modern humans into Eurasia, the more southerly branch migration across Australia and the southern Pacific is less well understood.
What’s most relevant today about the study of early human migrations is whether any of these human movements were connected to climate change and, if so, how. Earlier research has suggested that humans spread across the globe in four waves, each one driven by climate change. The new findings suggest the picture may be more complicated than that, though. The Harvard study is a classic example of how, for every question answered, more doors open and more questions are asked.

Evolutionary scientists are naturally excited by the new findings, but Lipson urges caution. The process is slow and painstaking, as it should be. He urges against jumping to quick conclusions until more DNA evidence is found.
“There is some older archaeological evidence from Asia,” Lipson told New Scientist. “And while our results suggest the earliest human inhabitants probably would not have been closely related to Asian and Australian populations today, it would be interesting to see DNA from those sites.”
What we do know, based on DNA connected from 142 populations around the world, is that all non-Africans appear to be descended from a single group that split from the ancestors of African hunter-gatherers while, within Africa itself, humans formed isolated groups and then separated from each other.
The first migration did not end there. The study suggests that, subsequent to that first migration, there was a series of slow-paced migrations spread out over a period of thousands of years. Early Homo sapiens first arrived in southern Europe 80,000 years ago — far earlier than previously believed.
Question remain. Thanks to this new study and studies like it, the plot has thickened.