Connect with us

The Conversation

Fossilized footprints reveal 2 extinct hominin species living side by side 1.5 million years ago

Published

on

theconversation.com – Anna K. Behrensmeyer, Senior Research Geologist and Curator of Vertebrate Paleontology, Smithsonian Institution – 2024-11-28 13:01:00

Excavating the new trackway site, with footprints from hominins, birds and other animals visible in foreground.
Neil Roach

Anna K. Behrensmeyer, Smithsonian Institution; Kevin Hatala, Chatham University, and Purity Kiura, National Museums of Kenya

Human footprints stir the imagination. They invite you to follow, to guess what someone was doing and where they were going. Fossilized footprints preserved in rock do the same – they record instants in the lives of many different extinct organisms, back to the earliest creatures that walked on four feet, 380 million years ago.

Discoveries in eastern Africa of tracks made by hominins – our ancient relatives – are telling paleontologists like ourselves about the behavior of hominin species that walked on two feet and resembled us but were not yet human like we are today. Our new research focuses on footprints that amazingly record two different species of hominins walking along the same Kenyan lakeshore at the same time, roughly 1.5 million years ago.

Studying ancient tracks like these fills in exciting pieces of the human evolution story because they provide evidence for hominin behavior and locomotion that scientists cannot learn from fossilized bones.

Finding first fossilized footprints in Kenya

The first discovery of tracks of early hominins in Kenya’s Lake Turkana region happened by chance in 1978. A team led by one of us (Behrensmeyer) and paleoecologist Léo Laporte was exploring the geology and fossils of the rich paleontological record of East Turkana. We focused on documenting the animals and environments represented in one “time slice” of widespread sediments deposited about 1.5 million years ago.

man squats on excavation surface, brushing with paintbrush
Kimolo Mulwa at the site of the first hominin footprint discovery in 1978. Deep, sand-filled depressions to his left show hippopotamus tracks in cross section.
Anna K. Behrensmeyer

We collected fossils from the surface and dug geological step trenches to document the sediment layers that preserved the fossils. The back wall of one of the trenches showed deep depressions in a layer of solidified mud that we thought might be hippo tracks. We were curious about what they looked like from the top down – what scientists call the “plan view” – so we decided to expose 1 square meter of the footprint surface next to the trench.

When I returned from more fossil bone surveys, Kimolo Mulwa, one of the expert Kenyan field assistants on the project, had carefully excavated the top of the mudstone layer and there was a broad smile on his face. He said, “Mutu!” – meaning “person” – and pointed to a shallow humanlike print in among the deep hippo tracks.

indentations on flat sediment surface
The excavated surface shows the hominin trackway along with footprints of hippos, a large bird and other animals. For the photo, scientists filled the hominin tracks and a few other footprints with dark sand so they would stand out against the light-colored sediment.
Anna K. Behrensmeyer

I could hardly believe it, but, yes, a humanlike footprint was clearly recognizable on the excavated surface. And there were more hominin tracks, coming our way out of the strata. It was awe-inspiring to realize we were connecting with a moment in the life of a hominin that walked here 1½ million years ago.

We excavated more of the surface and eventually found seven footprints in a line, showing that the hominin had walked eastward out of softer mud onto a harder, likely shallower surface. At one point the individual’s left foot had slipped into a deep hippo print and the hominin caught itself on its right foot to avoid falling – we could see this clearly along the trackway.

Comparison of a fossil footprint and a modern one
Comparison of the best-preserved 1978 hominin track, left, with a modern track (women’s size 7) made by Behrensmeyer on the muddy shoreline of Lake Turkana. The white objects inside the fossil footprint are calcified fillings of worm burrows or roots that formed in the sediment after the track was buried.
Anna K. Behrensmeyer

Even today on the shore of modern Lake Turkana, it’s easy to slip into hippo prints, especially if the water is a bit cloudy. We joked about being sorry our hominin track-maker didn’t fall on its hands, or face, so we could have a record of those parts, too.

Another set of tracks

Over four decades later, in 2021, paleontologist Louise Leakey and her Kenyan research team were excavating hominin fossils discovered in the same area when team member Richard Loki uncovered a portion of another hominin trackway. Leakey invited one of us (Hatala) and paleoanthropologist Neil Roach to excavate and study the new trackway, because of our experience working on other hominin footprint sites.

3D image of footprints pressed into a surface
A 3D image of part of the 2021 excavated surface made by photogrammetry, which shows the tracks of two hominin species crossing.
Kevin Hatala

The team, including 10 expert Kenyan field researchers led by Cyprian Nyete, excavated the surface and documented the tracks with photogrammetry – a method for 3D imaging. This is the best way to collect track surfaces because the sediments are not hard enough – what geologists call lithified – to remove from the ground safely and take to a museum.

The newly discovered tracks were made approximately 1.5 million years ago. They occur at an earlier stratigraphic level than the ones we found in 1978 and are about a hundred thousand years older, based on dating of volcanic deposits in the East Turkana strata.

aerial view of about a dozen people standing in a curve on a rocky bare landscape
Research team members along the perimeter of the ancient footprint trackway.
Louise N. Leakey

Who was passing through?

These footprints are especially exciting because careful anatomical and functional analysis of their shapes shows that two different kinds of hominins made tracks on the same lakeshore, within hours to a few days of each other, possibly even within minutes!

We know the footprints were made very close together in time because experiments on the modern shoreline of Lake Turkana show that a muddy surface suitable for preserving clear tracks doesn’t last long before being destroyed by waves or cracked by exposure to the Sun.

fossilized indentations of footprints receding into distance on sandy-looking ground
A trackway of footprints scientists hypothesize were created by a Paranthropus boisei individual.
Neil T. Roach

This is the first time ever that scientists have been able to say that Homo erectus and Paranthropus boisei – one our likely ancestor and the other a more distant relative – actually coexisted at the same time and place. Along with many different species of mammals, they were both members of the ancient community that inhabited the Turkana Basin.

Not only that, but with the new tracks as references, our analyses suggest that other previously described hominin tracks in the same region indicate that these two hominins coexisted in this area of the Turkana Basin for at least 200,000 years, repeatedly leaving their footprints in the shallow lake margin habitat.

Other animals left tracks there as well – giant storks, smaller birds such as pelicans, antelope and zebra, hippos and elephants – but hominin tracks are surprisingly common for a land-based species. What were they doing, returning again and again to this habitat, when other primates, such as baboons, apparently did not visit the lakeshore and leave tracks there?

silhouette of a tree with circles for about 20 hominin species, showing their relationships
The track-making species Homo erectus and Paranthropus boisei are on two different branches of the hominin family tree.
Smithsonian Human Origins Program, modified by author from original artwork

These footprints provoke new thoughts and questions about our early relatives. Were they eating plants that grew on the lakeshore? Some paleontologists have proposed this possibility for the robust Paranthropus boisei because the chemistry of its teeth indicate a specific herbivorous diet of grasslike and reedlike plants. The same chemical tests on teeth of Homo erectus – the ancestral species to Homo sapiens – show a mixed diet that likely included animal protein as well as plants.

The lake margin habitat offered food in the form of reeds, freshwater bivalves, fish, birds and reptiles such as turtles and crocodiles, though it could have been dangerous for bipedal primates 4 or 5 feet (1.2 to 1.5 meters) tall. Even today, people living along the shore occasionally are attacked by crocodiles, and local hippos can be aggressive as well. So, whatever drew the hominins to the lakeshore must have been worth some risk.

For now it’s impossible to know exactly how the two species interacted. New clues about their behavior could be revealed with future excavations of more trackway surfaces. But it is fascinating to imagine these two hominin “cousins” being close neighbors for hundreds of thousands of years.

people carrying water buckets at a sandy construction site in open landscape
Construction of the Ileret footprint site museum, with Daasanach women carrying water for mixing concrete.
National Museums of Kenya Audio Visual

Ancient footprints you can visit

Earlier excavations of hominin trackways near a village called Ileret, 25 miles (40 km) to the north of our new site, are being developed as a museum through a project by the National Museums of Kenya. The public, the local Daasanach people, educational groups and tourists will be able to see a large number of 1.5-million-year-old hominin footprints on one excavated surface.

That layer preserves tracks of at least eight hominin individuals, and we now believe they represent members of both Homo erectus and Paranthropus boisei. Among these is a subset of individuals, all about the same adult size, who were moving in the same direction and appear to have been traveling as a group along the lake margin.

The museum built over the track site is designed to prevent erosion of the site and to protect it from seasonal rains. A community outreach and education center associated with the museum aims to engage local educational groups and young people in learning and teaching others about this exceptional record of human prehistory preserved in their backyard. The new site museum is scheduled to open in January 2025.The Conversation

Anna K. Behrensmeyer, Senior Research Geologist and Curator of Vertebrate Paleontology, Smithsonian Institution; Kevin Hatala, Associate Professor of Biology, Chatham University, and Purity Kiura, Chief Research Scientist in Archaeology and Heritage, National Museums of Kenya

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read More

The post Fossilized footprints reveal 2 extinct hominin species living side by side 1.5 million years ago appeared first on theconversation.com

The Conversation

Trump’s opening tariff salvo will hurt US consumers − following through on Canada, Mexico threats will increase the price pain

Published

on

theconversation.com – Jason Reed, Associate Teaching Professor of Finance, University of Notre Dame – 2025-02-04 14:05:00

Trump’s opening tariff salvo will hurt US consumers − following through on Canada, Mexico threats will increase the price pain

Jason Reed, University of Notre Dame

If U.S. voters reelected Donald Trump hoping for relief from higher prices, his recent threats to impose tariffs on America’s three largest trade partners might make them think again.

On Saturday, Feb. 1, Trump announced 25% tariffs on Canada and Mexico and 10% tariffs on China, which he said would take effect on Tuesday, Feb. 4. While markets braced for the news to some degree, they still saw a steep premarket sell-off on Monday, Feb. 3, followed by morning volatility.

While Canada and Mexico negotiated monthlong reprieves on Monday, the new tariffs on China went into effect as expected Tuesday, Feb. 4. And while the ultimate shape of Trump’s tariff policy remains to be seen, the president warned that American consumers could feel “some pain” as a result.

Given my training as an economist and finance professor, I think Trump could be right on that score. In fact, if the tariffs go into effect, they could spell disaster for the Federal Reserve’s inflation reduction efforts.

From grocery stores to homes

U.S. consumers might be surprised to find out that almost every economic sector could be affected by this opening salvo of tariffs, should they go ahead in March. Imports from Mexico and Canada reached close to US$1 trillion in 2024, almost double the amount the U.S. imports from China.

The U.S. is particularly reliant on Mexico for fresh fruits and vegetables, and on Canada for lumber. So if the tariffs go into effect, Americans who have been waiting for home prices to ease may have to continue waiting, as tariffs on lumber and other building materials could worsen the affordable-housing crunch. And let’s not even talk about avocado prices.

Meanwhile, the 10% tariffs on Chinese goods will likely boost the price of electronics, and China has already imposed retaliatory measures. Trump has also proposed 25% tariffs on Taiwan and its semiconductor industry, in an attempt to push Taiwanese companies to invest more in U.S. manufacturing. If that tariff were to go into effect, prices for U.S. consumers would be even higher.

A tax by any other name …

Tariffs are an import tax. They’re passed through the supply chain in the form of higher prices and are eventually paid by consumers. Traditionally, governments have used tariffs as a fiscal tool to encourage businesses and consumers to move away from foreign-made products and support domestic businesses instead.

In theory, new tariffs could encourage foreign businesses to invest in the U.S. and make more stuff on American soil. Unfortunately, domestic manufacturing has seen a systemic decline since the 1980s, resulting in lower prices for consumers but severely limiting U.S.-produced products. In the short term, at least, import taxes on Canadian, Mexican and Chinese products would ultimately be paid by U.S. consumers.

Although this round of tariff threats may seem arbitrary to some, the Trump administration says it considers tariffs deeply intertwined with national security concerns. Stephen Miran, Trump’s pick to chair the president’s Council of Economic Advisers, has laid out a path for Trump’s tariff plan, which he says is aimed at putting American industry on fairer ground against the rest of the world.

In the long term, it’s unclear whether Trump’s threatened trade war will bring domestic manufacturing back to the U.S. and start a new industrial renaissance. In the meantime, American consumers will likely be stuck holding the bag.The Conversation

Jason Reed, Associate Teaching Professor of Finance, University of Notre Dame

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read More

The post Trump’s opening tariff salvo will hurt US consumers − following through on Canada, Mexico threats will increase the price pain appeared first on theconversation.com

Continue Reading

The Conversation

As allies prepare to strike back, a costly trade war looms

Published

on

theconversation.com – Bedassa Tadesse, Professor of Economics, University of Minnesota Duluth – 2025-02-04 13:43:00

Trump’s tariff gambit: As allies prepare to strike back, a costly trade war looms

Bedassa Tadesse, University of Minnesota Duluth

On Saturday, Feb. 1, 2025, U.S. President Donald Trump announced a plan to slap steep tariffs on imports from key American trading partners – 25% on goods from Mexico and Canada and 10% on imports from China. His stated reason? To curb illegal immigration and drug trafficking.

Both Mexico and Canada managed to buy some time. After urgent phone calls with Trump on Feb. 3, their leaders each secured a one-month reprieve. But Mexico’s Claudia Sheinbaum and Canada’s Justin Trudeau also made it clear to their U.S. counterpart: If these tariffs go through, they’ll hit back with their own trade restrictions. The world is watching the opening moves of what could become another costly trade war.

As a professor of economics, I can explain why this poses significant risks to the U.S. economy and American consumers. Economic theory suggests that tariffs distort market efficiency, raising production costs while limiting consumer choice and increasing prices.

Who really pays for tariffs?

While politicians often frame tariffs as a way to punish other countries, they actually hit domestic consumers and businesses hardest. Whether they’re facing higher grocery bills or disruptions in manufacturing, Americans will feel the strain.

When tariffs are imposed, companies must either absorb the additional costs – cutting into profits and potentially threatening jobs – or pass these costs to consumers through higher prices. Small businesses operating on thin profit margins are particularly vulnerable, as many lack the resources to quickly switch suppliers.

Tariffs trigger costly retaliation

Worse yet, such measures commonly set off a cycle of retaliation. During past trade disputes involving the U.S., affected nations have responded with counter-tariffs on American products, including textiles, steel and agricultural goods. Such retaliatory efforts have led to sharp declines in U.S. exports.

During the first Trump administration, for example, China imposed retaliatory tariffs on U.S. agricultural exports. As a result, the U.S. farmers lost billions of dollars, and the U.S. spent billions in government aid to offset those losses. China has already issued new tariffs on imports of U.S. goods and export controls on some of its exports to the U.S. to retaliate for Trump’s current move.

History also shows that trade wars are self-defeating. The Smoot-Hawley Tariff Act of 1930, which imposed tariffs on over 20,000 imported goods, prompted swift retaliation from trading partners and contributed to deepening the Great Depression.

Modern trade wars have other consequences

Modern trade wars hit closer to home than most Americans realize. The recent tariff threat against Colombia reveals why. In 2023, Colombian farmers supplied US$1.14 billion worth of fresh-cut flowers to U.S. florists. In a near-crisis that lasted a weekend, Trump threatened to slap steep tariffs on the South American nation, right when flower shops across America were stocking up for one of their busiest seasons: Valentine’s Day.

The same tariffs would have hit Colombian coffee too, affecting everything from neighborhood cafes to grocery store prices. This shows how modern trade disputes can instantly disrupt the everyday purchases Americans make.

Other key trading partners, including the European Union, have also come into the crosshairs. On Jan. 30, 2025, the president issued a stark warning to Brazil, Russia, India, China and South Africa – the so-called BRICS nations – threatening 100% tariffs if they continued efforts to reduce reliance on the U.S. dollar as their reserve currency.

These threats can do more than alienate strategic partners; they risk accelerating dedollarization – pushing nations to develop alternative financial systems that weaken U.S. influence in global trade.

A more effective approach

Beyond causing immediate economic pain, constant tariff threats risk damaging America’s credibility as a reliable trading partner. The U.S. helped establish the rules-based international trading system, but regular tariff threats erode global trust and push trading partners to seek alternatives to the U.S. market.

The reality is clear: No country in the modern era has successfully used tariffs to grow its economy or improve the well-being of its people. The countries that are most dependent on tariff revenues for their national budgets are among the world’s poorest and least developed economies.

I believe the path to maintaining America’s economic leadership lies in embracing a smarter, more strategic trade policy – one that builds alliances instead of breaking them. A strategy that prioritizes negotiation, fosters innovation and enhances competitiveness – and that doesn’t rely on protectionist tactics more often used by developing nations – would strengthen cooperation and stability, ensuring long-term economic prosperity.The Conversation

Bedassa Tadesse, Professor of Economics, University of Minnesota Duluth

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read More

The post As allies prepare to strike back, a costly trade war looms appeared first on theconversation.com

Continue Reading

The Conversation

Who are immigrants to the US, where do they come from and where do they live?

Published

on

theconversation.com – Jennifer Van Hook, Distinguished Professor of Sociology and Demography, Penn State – 2025-02-04 13:42:00

Who are immigrants to the US, where do they come from and where do they live?

Immigrants to the U.S. increasingly arrive like these people, seeking asylum at a formal border crossing, rather than trying to sneak across the border.
Carlos Moreno/NurPhoto via Getty Images

Jennifer Van Hook, Penn State

Undocumented immigration is a key issue in American politics, but it can be hard to nail down the basic facts about who these immigrants are, where they live and how their numbers have changed in the past few decades.

I study the demographics of the U.S. immigrant population and have seen how the data has changed over time. Here are some basics to set the stage as President Donald Trump begins his second term in office vowing to crack down hard on immigrants, including by conducting mass deportations.

Immigration status

My analysis of the Census Bureau’s 2023 American Community Survey data, in collaboration with the Migration Policy Institute, a nonpartisan nonprofit immigration research group, finds that as of the middle of 2023, approximately 51 million foreign-born people lived in the United States.

Most immigrants are in the U.S. legally. About 49% have become U.S. citizens by a process known as naturalization. Another 19% hold lawful permanent resident status and are eligible to become U.S. citizens through naturalization. Still another 5% are in the country on temporary visas, like those for international students, diplomats and their families, and seasonal or temporary workers.

The remaining 27% – around 13.7 million people – are outside those categories and therefore generally considered to be undocumented.

My analysis shows that the number of undocumented immigrants held steady at around 11 million between 2007 and 2019. In the next four years, the numbers increased by nearly 3 million. This recent growth is mostly attributable to large increases in border crossings by migrants from Central and South America who were seeking asylum or other forms of humanitarian relief. Starting in June 2024, however, the number of people entering across the U.S.-Mexico border fell back to normal levels when the Biden administration implemented the Secure the Border rule, which suspends asylum applications at the border when crossings reach a seven-day average of 2,500.

These changes were accompanied by changes in the undocumented migration process itself. In the past, undocumented immigrants often entered the country by slipping undetected across the U.S. border with Mexico. But increased border enforcement made the journey more dangerous and expensive.

Instead of paying smugglers or risking their lives in the desert, growing numbers of undocumented immigrants now either directly approach immigration officials at airports or land-border crossings and seek asylum in the U.S. Others are initially admitted to the country legally on a temporary tourist, student or work visa – but then overstay the time period for which they have permission.

Additionally, growing numbers of undocumented immigrants occupy what might be called a “liminal” or “in-between” status. The Migration Policy Institute analysis estimates this encompasses a range of groups as of the middle of 2023, including:

  • About 2.1 million people awaiting a decision on their asylum claims.
  • 521,000 parolees, allowed into the U.S. for humanitarian or national security reasons, like those paroled recently from Afghanistan and Ukraine.
  • 654,000 people who hold temporary protected status because it would be unsafe for them to return home due to armed conflict, natural disasters and other emergencies.
  • 562,000 who are protected by the Deferred Action for Childhood Arrivals program because they were brought to the United States as children by their parents.

The report estimates that just over one-quarter of undocumented immigrants currently occupy this type of “in-between” status. These immigrants are protected from deportation. Some even have a legal right to work in the U.S. Yet they do not possess a durable legal immigration status, and their rights could be threatened by policy changes.

While Trump says he wants to deport as many as 11 million immigrants, analyses published by The New York Times and The Washington Post indicate that it may be difficult to remove many of them under existing U.S. law. The one group that is easy to remove – those with a criminal record – is relatively small, numbering about 650,000.

Shifting countries of origin

Since 1980, Mexicans have been the largest single national origin group in the United States. I found that 10.9 million Mexican-born individuals were living in the country in 2023, making up 23% of all immigrants. The second-largest group, immigrants from India, numbered just 2.9 million, or 6% of all immigrants living in the U.S.

However, immigrants’ origins have been shifting away from Mexico.

With the onset of the Great Recession of 2007-2009, work opportunities in U.S. construction and manufacturing evaporated. Many Mexican laborers had been working in construction at the time but went back to Mexico when the U.S. housing market collapsed.

At that same time, Mexico’s economic conditions improved, its population growth slowed, and many would-be migrants opted to stay home. For the first time in decades, from 2007 to 2022 the number of Mexicans who returned home exceeded the number coming to the United States.

This trend was especially pronounced among undocumented immigrants. I found that Mexicans made up about 51% of the undocumented immigrants who arrived in the country 10 or more years ago. Central Americans made up 20%, and the remaining originated from other regions.

However, undocumented migrants now come from across the globe. Among undocumented immigrants who arrived within the past 10 years, 19% came from Mexico. Larger shares came from Central America and South America. While some of these new migrants seek work, others flee crime, economic and ecological disasters, and political persecution in their home countries.

Duration of residence

Most immigrants, whether they are in the U.S. legally or illegally, have lived in the United States for many years. Just under half of foreign-born individuals have lived in the country for two decades or more, and more than two-thirds have lived in the country for at least 10 years. Only 20% arrived within the past five years.

This is a dramatic change from the early 2000s, when less than 10% of immigrants had been in the U.S. for more than two decades, and more than one-third had arrived within the previous five years.

That means many of the people who are likely to be targeted for deportation in the coming months are settled, long-term members of American society.

Place of residence

As of 2023, 6.6 million immigrants reported on the Census Bureau’s American Community Survey that they moved to the United States in the past five years.

However, the effects of these new immigrants on American communities has been uneven. Although most communities are more racially and ethnically diverse now than in the past, the numbers of newly arrived immigrants are relatively low in most places.

Fifteen states host fewer than 20,000 immigrants, and 33 states are home to fewer than 100,000. In contrast, over half of new arrivals live in just five states: California, Florida, Illinois, New York and Texas are the home of over half of new arrivals yet have only 37% of the U.S. population. Other states such as Georgia, Michigan, New Jersey, North Carolina, Pennsylvania and Washington also are home to large and growing immigrant populations.

The U.S. immigrant population is changing rapidly. In the early years of the 21st century, Mexican immigrants dominated undocumented immigration flows to the United States. Decades later, many of these people continue to live in the country.

In the past four years, however, the flow of undocumented people increased dramatically. These new arrivals tend to come from troubled nations in Central and South America, many of whom are protected from deportation and have a legal right to work in the U.S. Altogether, most undocumented immigrants either have lived in the country for decades or have legal protections.

Neither of these groups fit the profile of undocumented immigrants who are typically targeted for deportation.The Conversation

Jennifer Van Hook, Distinguished Professor of Sociology and Demography, Penn State

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read More

The post Who are immigrants to the US, where do they come from and where do they live? appeared first on theconversation.com

Continue Reading

Trending