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How Did Human Language Evolve? Scientists Still Don’t Know

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Human language adaptations first appeared in our ancestors

Most scientists think language emerged in stages, as our ancestors evolved the necessary adaptations for speech. (Credit: Sergey Uryadnikov/shutterstock)

Humans have language and other animals don’t. That’s obvious, but how it happened is not. Since Darwin’s time, scientists have puzzled over the evolution of language. They can observe the present-day product: People today have the capacity for language, whether it be spoken, signed or written. And they can infer the starting state: The communication systems of other apes suggest abilities present in our shared ancestor.

But the million-dollar question is what happened in between. How did we transition from ape-like communication to full-fledged human language?

Most scientists think this happened in stages, as our ancestors evolved the adaptations needed for language. In earlier stages, human ancestors would have used a kind of protolanguage — more complex than ape communication, but lacking elements of modern language.

But what exactly was this protolanguage like? That’s where we hit considerable debate. Some researchers argue that our ancestors sang before they spoke. Others claim protolanguage was dominated by pantomimed gestures — a society built on charades.

Here, I’ll do my best to summarize prevailing models for language origins, drawing largely from a 2017 academic review by evolutionary biologist W. Tecumseh Fitch.

But first…

What Makes Language, Language

Before trying to explain how language evolved, we need to clarify exactly what evolved. We must define what language is and how it differs from the communication abilities of our closet evolutionary relatives, the great apes.

In human language, arbitrary sounds and signs represent specific words, which can be learned, invented and infinitely combined within grammatical structures. We can talk about anything we can think — plans, pancakes, politics — including what is not the case: “I have no plans to make pancakes or enter politics.” And many statements have specific meanings that are context dependent. For instance, “How are you?” can be a greeting, not a genuine inquiry. Language allows us to bond with others, or to deceive them. And although our native tongue is not innate, toddlers pick it up without conscious effort.

These qualities make language an extraordinary communication system found exclusively in humans. But the system can be dissected into components, or traits necessary for language. And these emerged at different times in our evolutionary past. Traits shared with other apes likely existed millions of years ago in our common ancestor. The traits we don’t see in other apes probably only emerged in hominins, the evolutionary branch that includes humans and our extinct relatives.

There are at least three elements of language only present in hominins:

First, is a fine-control over our vocal tracts. Other apes are likely born with a more limited repertoire of vocalizations. The difference comes down to how our brains are wired: Humans have direct connections between the neurons controlling our voice box and the motor cortex, the region of our brain responsible for voluntary movements. Brain scans show these connections are lacking in other primates.

Next is our tendency to communicate for the sake of communicating. To encapsulate this, biologist Fitch used the German word Mitteilungsbedürfnis, “the drive to share thoughts.” Whereas chimps use a finite set of calls and gestures to convey the essentials — food, sex and danger — humans talk to bond and exchange ideas, and strive to ensure we’re understood. Most researchers attribute this difference to an idea called “theory of mind,” the understanding that others have thoughts. Chimps demonstrate more limited theory of mind, whereas humans know that other humans think things — and we’re constantly using language to uncover and influence those thoughts.

The last difference is hierarchical syntax. Phrases and sentences have nested structure and these provide meaning beyond the simple sequence of words. For instance, take the sentence: “Chad, who was out to lunch with Tony, was late to the meeting.” Hierarchical syntax processing allows us to correctly interpret that Chad was late to the meeting, even though “Tony” is closer to the verb “was late.” Over 60 years ago and still today, linguist Noam Chomsky proposed hierarchical syntax as the key to language.

So hypotheses for language origins must explain (at least) these three traits: precise vocal learning and control, overtly social communication and hierarchical syntax.

Leading Views on Language Evolution

Now for the fun part: How did these components emerge, and eventually converge, to constitute language?

There are several prevailing views, which differ in terms of the evolutionary pressures favoring language adaptations, the order these adaptations arose and the nature of protolanguage along the way.

Some believe precise vocal control and learning was the first language trait to emerge in hominins — and not for speaking, but for singing. This idea of musical protolanguage comes from Darwin himself and has been modified over the years by different researchers. During this hypothetical singing stage of human evolution, our ancestors’ survival and/or reproductive success would have depended on serenading, in the context of maintaining social bonds, attracting mates or soothing infants. (Given my repulsion for acapella, I’d be evolutionarily unfit for this phase).

An alternate view envisions protolanguage characterized by gesture and pantomime. In this case, syntax and social communication would have preceded vocal prowess. The strength of the gestural hypothesis is that our closest relatives, chimpanzees, exhibit more controlled and variable gestures (over 70 and counting) than calls (4 types and more hard-to-distinguish subtypes). The weakness of this view is, it’s unclear why or how language became so speech-dominate.

Others, convinced that hierarchical syntax emerged last, propose a protolanguage with symbolic words, but no complex, nested sentences. According to this view, our pre-linguistic ancestors talked more like babies — “Water! Thirsty!” — or pop-culture’s image of cavemen — “Me hunt mammoth. Me want sex.”

These models aren’t mutually exclusive. Some researchers integrate them into successive stages, associated with different hominin species. Perhaps between 2 and 4 million years ago, Australopiths like Lucy were gifted singers. By 1.9 million years ago Homo erectus combined gestures and expressive vocalizations into group rituals. And hierarchical syntax only emerged some 200,000- 300,000 years ago with the appearance of our species, Homo sapiens.

This might all sound like speculation (and some scientists dismiss it as such, e.g. this commentary or Chomsky’s quote here). But many researchers beg to differ: Scientific models of language evolution derive from evidence gathered in comparative biology, neuroscience, genetics, linguistics and paleoanthropology. This includes data on how animals communicate, the brain and gene systems underlying language, the complexity of artifacts in the archaeological record and changes in anatomy and brain size, preserved in fossils. Most importantly, the models make predictions for future research — what should be found if that’s really how language origins went down.

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Ecology

Globe Climate: Canada’s resource reckoning is coming

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Good afternoon, and welcome to Globe Climate, a newsletter about climate change, environment and resources in Canada.

This afternoon, the Alberta government announced that it is restoring a coal mining policy it revoked last spring. At the time, the move provoked a widespread public backlash detailed by The Globe. The original decision, which opened up more than 1.4 million hectares to exploration, was made without public consultation. Premier Jason Kenney previously defended the changes.

Lots more on coal and Canada’s resources industry in this week’s newsletter edition.

Now, let’s catch you up on other news.

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Ecology

‘Incredibly destructive’: Canada’s Prairies to see devastating impact of climate change

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As the climate continues to warm at an alarming rate, experts warn if dramatic steps to mitigate global warming are not taken, the effects in Canada’s Prairie region will be devastating to the country’s agriculture sector.

According to Environment and Climate Change Canada, the country is warming, on average, about double the global rate.

Scientists with the National Oceanic and Atmospheric Administration in the U.S. recently found 2020 was earth’s second-hottest year on record, with the average land and ocean surface temperature across the globe at 0.98 of a degree C above the 20th-century average.

However, the agency found the northern hemisphere saw its hottest year on record, at 1.28 degrees C above the average.

“(In Canada) we are looking at about 6.4C degrees of warming this century, which isn’t much less than one degree per decade, which is just a terrifying rate of warming,” Darrin Qualman, the director of climate crisis policy and action at the National Farmer’s Union said.

Qualman said there is “massive change coming” to Canada’s Prairies, which will be “incredibly destructive.”

“It’s not going too far to say that if we made that happen, parts of the Prairies wouldn’t be farmable anymore,” he said.

According to the federal government, in 2018 Canada’s agriculture and agri-food system generated $143 billion, accounting for 7.4 per cent of the country’s GDP.

The sector employed 2.3 million people in 2018. The majority of the 64.2 million hectares of farmland in Canada is concentrated in the Prairies and in southern Ontario.

The effects of climate change are already being felt on the ground in the Prairies, Qualman said, adding that the NFU has already heard from farmers complaining of “challenging weather.”

“People are sharing pictures of flattened crops and buildings, et cetera, that have been damaged,” he said. “And we’re still at the beginning of this.”

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Ecology

Insect-based dog food aims to cut your pet’s carbon pawprint

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Meat has an enormous carbon footprint, with livestock liable for about 15 per cent of worldwide emissions, as we have beforehand mentioned on this e-newsletter. That is prompted specialists to suggest consuming much less meat for sustainability (and well being) causes.

However what about your pet? One research discovered that the methane and nitrous oxide emissions generated by canine and cat meals within the U.S. alone had been equal to about 64 million tonnes of CO2, or roughly the quantity produced by 13.6 million automobiles. And it might be getting worse, with a development towards feeding pets “human-grade” meat.

That is prompted some pet meals makers to look to lower-carbon protein sources — together with bugs.

Research present that producing insect-based meals requires far much less feed, land and water and generates far fewer greenhouse fuel emissions per kilogram than meats comparable to beef, pork or rooster.

That is one of many causes increasingly more pet meals containing insect protein are hitting the market. Purina, a model owned by multinational Nestlé, launched a line of canine and cat meals containing black soldier fly larvae in Switzerland in November.

In Canada, Montreal-based Wilder Harrier began promoting canine treats made with cricket protein in 2015 and pet food made with black soldier fly larvae in 2019. It plans to broaden to launch a line of insect-based cat treats later this yr and cat meals in 2022 due to “a ton of demand,” mentioned firm co-founder Philippe Poirier.

Wilder Harrier initially labored with animal nutritionists on insect-based merchandise to unravel a unique downside — specifically, the founders’ canines had allergy symptoms to frequent meats utilized in canine meals. Poirier mentioned now about half its prospects hunt down the product due to their pets’ allergy symptoms and about half for environmental causes.

Dr. Cailin Heinze, a U.S.-based veterinary nutritionist licensed by the American School of Veterinary Vitamin, has written concerning the environmental influence of pet meals. She mentioned we’re typically “not as involved as we probably ought to [be]” concerning the environmental footprint of pets.

Alternatively, she famous that the longer-term influence of newer diets, comparable to vegan meals and people containing bugs, hasn’t been nicely examined in comparison with conventional pet meals.

Maria Cattai de Godoy, an assistant professor of animal sciences on the College of Illinois who research novel proteins for pet meals (together with bugs, yeast and plant-based substances), mentioned such substances are rigorously examined to find out their security and diet earlier than being added to pet meals. 

“This can be a very extremely regulated trade,” she mentioned, however admitted it is also evolving.

Relating to bugs, she mentioned constructive information “reveals promise in direction of utilizing them increasingly more in pet meals.” Insect-based proteins have additionally earned the endorsement of the British Veterinary Affiliation, which says some insect-based meals could also be higher for pets than prime steak.

However Godoy famous that there isn’t any one-size-fits-all resolution, and pet homeowners ought to take into consideration the wants of their very own particular person pet and analysis whether or not a specific weight loss plan can be appropriate.

She mentioned that other than the kind of protein, issues like packaging and manufacturing strategies may also make a distinction. For instance, utilizing meat byproducts that may in any other case turn into waste would not drive elevated meat manufacturing the identical approach as utilizing human-grade meat.

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