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Domesticating horses had a huge impact on human society − new science rewrites where and when it first happened

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theconversation.com – William Taylor, Assistant Professor and Curator of Archaeology, University of Colorado Boulder – 2024-09-03 08:01:44

Horses supported travel, communication, agriculture and warfare across much of the ancient world.

Wolfgang Kaehler/LightRocket via Getty Images

William Taylor, University of Colorado Boulder

Across human history, no single animal has had a deeper impact on human societies than the horse. But when and how people domesticated horses has been an ongoing scientific mystery.

Half a million years ago or more, early human ancestors hunted horses with wooden spears, the very first weapons, and used their bones for early tools. During the late Paleolithic era, as far back as 30,000 years ago or more, ancient artists chose wild horses as their muse: Horses are the most commonly depicted animal in Eurasian cave art.

Following their first domestication, horses became the foundation of herding life in the grasslands of Inner Asia, and key leaps forward in technology such as the chariot, saddle and stirrup helped make horses the primary means of locomotion for travel, communication, agriculture and warfare across much of the ancient world. With the aid of ocean voyages, these animals eventually reached the shores of every major landmass – even Antarctica, briefly.

As they spread, horses reshaped ecology, social structures and economies at a never-before-seen scale. Ultimately, only industrial mechanization supplanted their near-universal role in society.

Because of their tremendous impact in shaping our collective human story, figuring out when, why and how horses became domesticated is a key step toward understanding the world we live in now.

Doing so has proven to be surprisingly challenging. In my new book, “Hoof Beats: How Horses Shaped Human History,” I draw together new archaeological evidence that is revising what scientists like me thought we knew about this story.

bones wrapped in fabric on the grass, with statues of horses in the background

Horses have long been revered in the steppes of Inner Asia, as seen by the horse skulls and prayer flags at this monument to racehorses in central Mongolia.

William Taylor

A horse domestication hypothesis

Over the years, almost every time and place on Earth has been suggested as a possible origin point for horse domestication, from Europe tens of thousands of years ago to places such as Saudi Arabia, Anatolia, China or even the Americas.

By far the most dominant model for horse domestication, though, has been the Indo-European hypothesis, also known as the “Kurgan hypothesis.” It argues that, sometime in the fourth millennium BCE or before, residents of the steppes of western Asia and the Black Sea known as the Yamnaya, who built large burial mounds called kurgans, hopped astride horses. The newfound mobility of these early riders, the story goes, helped catalyze huge migrations across the continent, distributing ancestral Indo-European languages and cultures across Eurasia.

But what’s the actual evidence supporting the Kurgan hypothesis for the first horse domestication? Many of the most important clues come from the bones and teeth of ancient animals, via a discipline known as archaeozoology. Over the past 20 years, archaeozoological data seemed to converge on the idea that horses were first domesticated in sites of the Botai culture in Kazakhstan, where scientists found large quantities of horse bones at sites dating to the fourth millennium BCE.

Other kinds of compelling circumstantial evidence started to pile up. Archaeologists discovered evidence of what looked like fence post holes that could have been part of ancient corrals. They also found ceramic fragments with fatty horse residues that, based on isotope measurements, seem to have been deposited in the summer months, a time when milk could be collected from domestic horses.

The scientific smoking gun for early horse domestication, though, was a set of changes found on some Botai horse teeth and jawbones. Like the teeth of many modern and ancient ridden horses, the Botai horse teeth appeared to have been worn down by a bridle mouthpiece, or bit.

Together, the data pointed strongly to the idea of horse domestication in northern Kazakhstan around 3500 BCE – not quite the Yamnaya homeland, but close enough geographically to keep the basic Kurgan hypothesis intact.

There were some aspects of the Botai story, though, that never quite lined up. From the outset, several studies showed that the mix of horse remains found at Botai were unlike those found in most later pastoral cultures: Botai is evenly split between male and female horses, mostly of a healthy reproductive age. Killing off healthy, breeding-age animals like this on a regular basis would devastate a breeding herd. But this demographic blend is common among animals that have been hunted. Some Botai horses even have projectile points embedded in their ribs, showing that they died through hunting rather than a controlled slaughter.

These unresolved loose ends loomed over a basic consensus linking the Botai culture to horse domestication.

upper and lower jaws of a horse, showing teeth

Horse bones from archaeological sites hold clues about humanity’s earliest relationship with horses.

Peter Bittner

New scientific tools raise more questions

In recent years, as archaeological and scientific tools have rapidly improved, key assumptions about the cultures of Botai, Yamnaya and the early chapters of the human-horse story have been overturned.

First, improved biomolecular tools show that whatever happened at Botai, it had little to do with the domestication of the horses that live today. In 2018, nuclear genomic sequencing revealed that Botai horses were not the ancestors of domestic horses but of Przewalski’s horse, a wild relative and denizen of the steppe that has never been domesticated, at least in recorded history.

Next, when my colleagues and I reconsidered skeletal features linked to horse riding at Botai, we saw that similar issues are also visible in ice age wild horses from North America, which had certainly never been ridden. Even though horse riding can cause recognizable changes to the teeth and bones of the jaw, we argued that the small issues seen on Botai horses can reasonably be linked to natural variation or life history.

This finding reopened the question: Was there horse transport at Botai at all?

man looks at large jaw bone with teeth under a bright light

Researcher Chance Ward examines a horse jawbone in an archaeology laboratory in Wyoming.

Peter Bittner

Leaving the Kurgan hypothesis in the past

Over the past few years, trying to make sense of the archaeological record around horse domestication has become an ever more contradictory affair.

For example, in 2023, archaeologists noted that human hip and leg skeletal problems found in Yamnaya and early eastern European burials looked a lot like problems found in mounted riders, consistent with the Kurgan hypothesis. But problems like these can be caused by other kinds of animal transport, including the cattle carts found in Yamnaya-era sites.

So how should archaeologists make sense of these conflicting signals?

A clearer picture may be closer than we think. A detailed genomic study of early Eurasian horses, published in June 2024 in the journal Nature, shows that Yamnaya horses were not ancestors of the first domestic horses, known as the DOM2 lineage. And Yamnaya horses showed no genetic evidence of close control over reproduction, such as changes linked with inbreeding.

Instead, the first DOM2 horses appear just before 2000 BCE, long after the Yamnaya migrations and just before the first burials of horses and chariots also show up in the archaeological record.

three people crouch on slushy ground with a large white jawbone visible in between

Archaeologists investigate an ancient horse jawbone melting from mountain ice in western Mongolia.

Yancen Diemberger, CC BY-ND

For now, all lines of evidence seem to converge on the idea that horse domestication probably did take place in the Black Sea steppes, but much later than the Kurgan hypothesis requires. Instead, human control of horses took off just prior to the explosive spread of horses and chariots across Eurasia during the early second millennium BCE.

There’s still more to be settled, of course. In the latest study, the authors point to some funny patterns in the Botai data, especially fluctuations in genetic estimates for generation time – essentially, how long it takes on average for a population of animals to produce offspring. Might these suggest that Botai people still raised those wild Przewalski’s horses in captivity, but only for meat, without a role in transportation? Perhaps. Future research will let us know for sure.

Either way, out of these conflicting signals, one consideration has become clear: The earliest chapters of the human-horse story are ready for a retelling.The Conversation

William Taylor, Assistant Professor and Curator of Archaeology, University of Colorado Boulder

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Rents rise faster after disasters, but a federal program can help restrain excesses

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theconversation.com – Anthony W. Orlando, Assistant Professor of Finance, Real Estate and Law, California State Polytechnic University, Pomona – 2025-01-14 13:02:00

Two people embrace on Jan. 9, 2025, in Altadena, Calif., amid property destroyed by the Eaton Fire.
Justin Sullivan/Getty Images

Anthony W. Orlando, California State Polytechnic University, Pomona

The wildfires raging across Los Angeles are setting the scene for a real estate nightmare.

Thousands of homes and other structures are destroyed and hundreds of thousands of residents have been evacuated at various times. Many will not return for months, if ever. Homeless in an instant, they are now flooding the housing market, desperately seeking shelter.

The Los Angeles housing market is poorly equipped for this crisis. It is already one of the nation’s most expensive markets to buy or rent a place to live, largely due to a significant and growing shortage of affordable housing. That shortage will become only more dire with the destruction of so many fire-ravaged buildings.

For the past two years, I have been studying the effects of natural disasters like this one on rental housing markets. As a professor of real estate, I have analyzed the question from a distance, sifting through data.

This time, however, as a resident of Pasadena, I have seen the carnage up close. I watched the Eaton Fire spread across the mountains from my back porch. I helped friends evacuate before their neighborhood was consumed in flames. Now, they’re sitting at my dining table as they process what they’ve lost and search for a new place to live.

Unfortunately, from my research, I have no doubts about what comes next.

Why disasters drive up rents

Scarcity is the enemy of affordability. This is one of the central tenets of economics. When too many people chase too few goods, prices rise.

So, you might expect that a natural disaster, which destroys housing and inundates the remaining units with new renters, would drive up rents, at least in the short run.

That is exactly what my research has found – but it’s not just the short run.

Two years ago, I worked with a team of researchers to prepare a report for the Brookings Institution, where we compiled a database of natural disasters across a variety of major markets throughout the country from 2000 to 2020. We measured the change in rents in places such as Atlanta, Detroit, Miami and San Francisco that landlords were asking for apartments in disaster-impacted neighborhoods. We then compared those cities with similar neighborhoods that weren’t impacted by the disasters.

We found that natural disasters increased rents during those two decades by 4% to 6%. That means rents were at least 4% higher than they would have been in the absence of the disaster.

These rent hikes were especially clear and pernicious after wildfires in California.

These weren’t just short-term effects. It took 18 months for the full effects to be felt in the market, and they never fully went away. Even four years after the disaster, renters were still paying 2% to 3% more than they would have been without the disaster.

In short, we found that disasters permanently change rental housing markets. They eliminate older, affordable housing, allowing developers to build newer, higher-end and even luxury housing in its place. Those changes drive up insurance costs, and the disasters motivate cities to adopt stricter building codes that in turn add to construction costs for the sake of weathering future disasters better.

How much rents increase, however, depends on how communities and the authorities respond to the disaster.

A burnt-out area following a big fire.
Burned homes are seen from above near the Los Angeles neighborhood of Pacific Palisades on Jan. 9, 2025, after massive fires engulfed whole neighborhoods and displaced thousands of people.
Josh Edelson AFP via Getty Images

Federal aid can slow the growth of rents

We found that rents did not grow as fast when the government stepped in to help.

Specifically, we investigated markets where Congress had used the Community Development Block Grant Disaster Recovery – CDBG-DR – program, providing grants through the Department of Housing and Urban Development. This federal funding typically comes with strings attached and “rental requirements” often mandating that a significant portion of the money be used to build affordable housing.

At least one of these disaster relief grants was issued every year from 2003 to 2020. In some years, Congress allocated as many as 27 different grants across the country to different disaster-impacted areas.

In these markets, we found that rents still rose after disasters – but at a significantly slower pace than in the markets where Congress didn’t send these disaster relief funds.

We dug deeper into several case studies in 2024 to understand why the CDBG-DR program is associated with lower rent hikes over the long run. In this new study, we found that housing markets that benefited from these disaster relief grants were able to build more rental units, easing the housing shortage. They improved affordability by tackling the scarcity problem directly.

Rental units were the key to solving the rent crisis. These cities, where affordability was better post-disaster, didn’t build more single-family homes than the other cities. They built more apartment units.

In these markets, these disaster relief grants saved the average renter between $780 and $1,080 in annual housing costs in 2023.

We believe that this finding shows why it is important not only to rebuild the houses destroyed in disasters like the Los Angeles fires but also to create new rental opportunities in all kinds of housing.

Hope in the aftermath

Here in Los Angeles, the clock is already ticking.

News reports are mounting of landlords raising rents to eye-popping levels.

Fortunately, there are government policies and programs that can help Angelenos find shelter today and that may help the Los Angeles housing market not get even less affordable tomorrow.The Conversation

Anthony W. Orlando, Assistant Professor of Finance, Real Estate and Law, California State Polytechnic University, Pomona

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How the CIA director helps the US navigate a world of spies, threats and geopolitical turbulence

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theconversation.com – Matthew Clary, Senior Lecturer in Political Science, Auburn University – 2025-01-14 12:44:00

The CIA is the U.S.’s premiere spy agency.
Mark Wilson/Getty Images

Matthew Clary, Auburn University

Today, the United States is navigating an increasingly unsettled world. The positions advising the president on national security are as important as ever. One such position, the director of the Central Intelligence Agency, is key to providing the president and Cabinet with timely intelligence and analysis.

So, what is the job of director of the CIA? What role does the director play in U.S. national security? How has the position changed over time?

The CIA’s role in national security

The CIA director leads the government agency responsible for conducting espionage and covert action. The CIA director is a Cabinet level position but reports to the director of national intelligence.

The CIA was established by the National Security Act of 1947 as America’s premiere civilian-led foreign intelligence agency. The agency carries out espionage and covert action exclusively outside the U.S.

The CIA is organized into five directorates – analysis, operations, science and technology, digital innovation, and support – and 11 regional and topical mission centers. The number of CIA employees is classified.

Espionage activities include the use of spies tasked with collecting useful information from influential people in countries around the world. This information, referred to as human intelligence, often provides depth and context about threats posed to the U.S.

In addition to collecting intelligence, the CIA analyzes and interprets it. The agency employees thousands of expert analysts who assess the information’s implications for U.S. national security. It is this in-depth analysis that is often presented to the president and Cabinet to inform their decision-making.

Covert action is an activity intended to influence political, economic or military conditions abroad without the role of the U.S. being apparent. Such actions include programs such as disinformation campaigns, counterterrorism operations and military raids such as the one used to kill 9/11 attack organizer Osama bin Laden.

a group of people stand in front of a wall with a three-story concrete building in the background
The CIA tracked 9/11 attack mastermind Osama bin Laden to this house in Pakistan, where U.S. special operations forces killed him.
AP Photo/B.K. Bangash

During the Cold War, from 1947 to 1991, the agency conducted numerous controversial covert actions. These included conducting coups in Iran and Guatemala and attempted or successful political assassinations in Congo, the Dominican Republic, Chile and Cuba. It also carried out highly effective programs such as the U-2 spy plane and Operation Argo, which rescued six Americans stranded in Iran after the 1979 revolution.

Effective espionage and covert action are likely to prove crucial for blunting threats that nations such as China, Russia, Iran and North Korea pose to the U.S. They will be key to monitoring the activities of these nations and enabling the director to deliver timely and valuable analysis to the president.

CIA director’s changed role

During the Cold War, the director of central intelligence had autonomy to conduct these covert actions with limited oversight. The position was extremely powerful at the time because the director was in charge of overseeing all U.S. intelligence activities, not just those of the CIA. This left the director of the CIA as the primary voice on intelligence matters to the president.

Since significant reform of the U.S. intelligence community in 2005 in response to the failure to prevent the 9/11 attacks, the role of the CIA director has changed. The most significant of these changes is that the CIA director no longer manages all U.S. intelligence. The reforms gave that responsibility to the more independent director of national intelligence.

The reform also saw the CIA director’s influence diminished because the position is no longer the primary intelligence adviser to the president. This has created tension between the two positions at times, with the CIA maintaining a high degree of independence from even the director of national intelligence.

In 2017, for example, President Donald Trump restored the CIA director as a formal member of the president’s Cabinet. Later, the CIA director was made a regular attendee of the National Security Council, the president’s principal forum for national security deliberations.

While there is more oversight of the CIA today from Congress and the director of national intelligence, the agency remains relatively independent in conducting espionage and covert action. These include covert actions during the Syrian civil war and during Russia’s invasion of Ukraine.

black and white photo of armed men around a boat on a beach
These Cuban soldiers helped defeat the CIA-organized Bay of Pigs invasion in Cuba in 1961.
Keystone/Getty Images

Another change has been the increased size of the intelligence community. The CIA today is only part of a much larger group of intelligence agencies. These include the Federal Bureau of Investigation, the Defense Intelligence Agency, the National Security Agency and more specialized agencies like the National Geospatial-Intelligence Agency.

In spite of this more capable and larger intelligence community, the CIA remains the premiere U.S. intelligence agency. This ensures that the CIA director will remain a key player in any presidential administration. The director possesses an immense responsibility to protect the U.S. from foreign threats.

Although the CIA director’s role has changed over time, what remains clear is its central importance to the success of U.S. national security efforts. This has become only more apparent given the increasing turbulence in world affairs.

This story is part of a series of profiles of Cabinet and high-level administration positions.The Conversation

Matthew Clary, Senior Lecturer in Political Science, Auburn University

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Terrorist groups respond to verbal attacks and slights by governments with more violence against civilians

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theconversation.com – Brandon J. Kinne, Professor of Political Science, University of California, Davis – 2025-01-14 07:48:00

Yazidi women in Iraq mourn the victims of Islamic State group attacks.
Ismael Adnan/SOPA Images/LightRocket via Getty Images

Brandon J. Kinne, University of California, Davis; Iliyan Iliev, The University of Southern Mississippi, and Nahrain Bet Younadam, University of Arizona

After an Islamic State group-inspired attack in New Orleans killed 14 people on New Year’s Day 2025, President Joe Biden warned that terrorists would find “no safe harbor” in the U.S.

Governments often condemn terrorist groups in this way, as well as making threats and engaging in what we call “verbal attacks.”

But such an approach may be counterproductive; extremist groups tend to respond to such comments by ratcheting up violence against civilians. That’s what we found when we analyzed six years of data on incidents of terrorist violence and their proximity to government denunciations.

Our study focused primarily on the Islamic State group.

The extremist organization came to the world’s attention in early 2014, when it began seizing territory in Iraq and Syria. At the height of its power in 2015, the Islamic State group controlled over 100,000 square kilometers (39,000 square miles).

Although it has declined substantially since then, the group remains the world’s deadliest terror organization – responsible for nearly 2,000 deaths in 2023.

The rapid metastasis of the Islamic State group – it has affiliates across the Middle East, North Africa and South Asia – combined with the extreme brutality of its tactics, triggered waves of condemnations by foreign governments. Former U.S. president Barack Obama initially referred to the Islamic State group as the “JV team” in 2014, implying that the group was not as formidable an opponent as more established groups like al-Qaida. A year later, he vowed to “destroy” the group.

Our motivating research question is whether these and similar statements affect terrorists’ behavior.

Traditionally, researchers have dismissed statements like this as “cheap talk.” And government officials similarly do not take seriously the possibility that such statements might have unintended consequences or inflict actual costs.

But when extremist groups commit terror attacks, they always have an audience in mind. And the Islamic State group closely monitors how governments respond to its actions.

Terrorist groups use attacks on civilians to illustrate the extreme measures they are willing to take to achieve their goals. Our research suggests that when governments denounce terrorists, reject their demands or make retaliatory threats, targeted groups infer that they are not being taken seriously. As a result, they commit further atrocities against civilians, with the intent of signaling their intentions and capabilities even more forcefully.

To confirm this, we used a large-scale machine-coded dataset known as the Integrated Crisis Early Warning System to extract daily data on all events involving the Islamic State group for the period 2014 to 2020. We then employed a coding system known as CAMEO to identify events where governments threatened, denounced or otherwise verbally attacked the group.

We found that when governments initiated any form of verbal attack against the organization, the Islamic State group responded by targeting civilians, typically within two days of a verbal attack.


Iliyan Iliev, Nahrain Bet Younadam, Brandon J Kinne, CC BY-SA

Our model showed that every three verbal attacks by governments led to an additional, otherwise unexpected attack by the Islamic State group on civilians. These attacks averaged over six deaths per attack, so the humanitarian consequences of this effect are substantial.

Why it matters

Government leaders face enormous pressures to address national security threats, and terrorism is a powerful source of anxiety for citizens.

Yet, counterterrorism is expensive, risky and logistically difficult.

As such, publicly threatening or denouncing an organization offers a tempting alternative strategy. But there has been little research into how government leaders’ words might backfire, encouraging extremists to attack civilians.

At the same time, although the Islamic State group has diminished greatly in capacity, transnational terrorism continues to flourish. And the resurgence of the Islamic State group remains a threat to security in the Middle East and beyond.

What still isn’t known

We extended the analysis to the terrorist groups Boko Haram in Nigeria and Al-Qaida in Iraq, and we found similar results. But further research is needed to determine whether this pattern holds for terrorist groups in general.

Our theory argues that extremists respond so strongly to verbal attacks because they view those remarks as questioning the group’s credibility – a phenomenon we refer to as a “credibility deficit.”

But terrorists have many motivations, including the desire to control territory and repress dissent. We don’t yet know the magnitude of these influences relative to credibility.

The Research Brief is a short take on interesting academic work.The Conversation

Brandon J. Kinne, Professor of Political Science, University of California, Davis; Iliyan Iliev, Associate Professor of Political Science, The University of Southern Mississippi, and Nahrain Bet Younadam, Postdoctoral Research Associate in the School of Government and Public Policy, University of Arizona

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