The Times Australia
The Times World News

.
The Times Real Estate

.

Revelations from 17-million-year-old ape teeth could lead to new insights on early human evolution

  • Written by Tanya M. Smith, Professor in the Australian Research Centre for Human Evolution & Griffith Centre for Social and Cultural Research, Griffith University
Revelations from 17-million-year-old ape teeth could lead to new insights on early human evolution

The timing and intensity of the seasons shapes life all around us, including tool use[1] by birds, the evolutionary diversification[2] of giraffes, and the behaviour[3] of our close primate relatives.

Some scientists suggest early humans and their ancestors also evolved due to rapid changes[4] in their environment, but the physical evidence to test this idea has been elusive – until now.

After more than a decade of work, we’ve developed an approach that leverages tooth chemistry and growth to extract information about seasonal rainfall patterns from the jaws of living and fossil primates.

We share our findings in a collaborative study[5] just published in Proceedings of the National Academy of Sciences.

Teeth are environmental time machines

During childhood our teeth grow in microscopic layers[6] similar to the growth rings found in trees. Seasonal changes in the world around us, such as droughts and monsoons, influence our body chemistry. The evidence of such changes is recorded in our teeth.

That’s because the oxygen isotope composition of drinking water naturally varies[7] with temperature and precipitation cycles. During warm or dry weather, surface waters accumulate more heavy isotopes of oxygen. During cool or wet periods, lighter isotopes become more common.

These temporal and climatic records remain locked inside fossilised tooth enamel, which can maintain chemical stability[8] for millions of years. But the growth layers are generally so small that most chemical techniques can’t measure them.

To get around this problem, we teamed up with geochemist Ian Williams at the Australian National University, who runs the world-leading Sensitive High Resolution Ion Microprobe[9] (SHRIMP) facilities.

In our study, we collected detailed records of tooth formation and enamel chemistry from slices of more than two dozen wild primate teeth from equatorial Africa.

We also analysed two fossil molars from an unusual large-bodied ape called Afropithecus turkanensis that lived in Kenya 17 million years ago. Diverse groups of apes inhabited Africa during this period, roughly 10 million years before the evolution of our early ancestors, the hominins.

Thin slice of a 17-million-year-old Afropithecus tooth illuminated with polarised light reveals progressive growth (right to left). We microsampled oxygen isotopes weekly for over three years, or 1148 days, in this tooth. Tanya M. Smith

Diving into an ancient African landscape

Several aspects of our research are helpful for understanding the link between environmental patterns and primate evolution.

First, we observe a direct relationship between historic African rainfall patterns and primate tooth chemistry. This is the first test of a highly influential idea in archaeological and earth sciences applied to wild primates: that teeth can record fine details of seasonal environmental change.

We are able to document annual west African rainy seasons and identify the end of east African droughts. In other words, we can “see” the storms and seasons that occur during an individual’s early life.

And this leads into another important aspect. We provide the largest record of primate oxygen isotope measurements collected so far, from diverse environments in Africa that may have resembled those of ancestral hominins.

Lastly, we’ve been able to reconstruct annual and semi-annual climate cycles, and marked environmental variation, from information held within the teeth of the two fossil apes.

Our observations support the hypothesis that Afropithecus developed certain features to adapt to a seasonal climate and challenging landscape. For example, it had specialised dental traits for hard object feeding, as well as a longer period of molar growth compared with earlier apes and monkeys – consistent with the idea that it consumed more seasonally varied foods.

Oxygen isotopes from the teeth of Afropithecus reveal wet and dry seasons that occurred 17 million years ago in eastern Africa. Daniel R. Green & Tanya M. Smith

We conclude our work by comparing data from Afropithecus to earlier studies of fossil hominins and monkeys from the same region in Kenya. Our detailed microsampling shows just how sensitive tooth chemistry is to fine-scale climate variation.

Previous studies of more than 100 fossil teeth have missed the most interesting part of oxygen isotope compositions in teeth: the huge seasonal variation on the landscape.

Read more: What teeth can tell about the lives and environments of ancient humans and Neanderthals[10]

Research potential closer to home

This novel research approach, coupled with our fossil ape findings and modern primate data, will be crucial for future studies of hominin evolution – especially in Kenya’s famous Turkana Basin.

For example, some researchers have suggested that seasonal differences in foraging[11] and stone tool use[12] helped hominins evolve and coexist in Africa. This idea has been hard to prove or disprove, in part because seasonal climatic processes have been hard to tease out of the fossil record.

Our approach could also be extended to animal remains from rural Australia to gain further insight into historic climate conditions, as well as the prehistoric environmental changes that shaped Australia’s unique modern landscapes.

Read more: Archaeology can help us prepare for climates ahead – not just look back[13]

Read more https://theconversation.com/revelations-from-17-million-year-old-ape-teeth-could-lead-to-new-insights-on-early-human-evolution-187996

The Times Features

The Best Adjustable Bed and Mattress Packages for Comfort

The appropriate bed and mattress are essential for establishing the perfect sleep environment. If you seek a way to upgrade your sleep experience, adjustable bed and mattress pac...

Designing a Modern Home: Features That Will Make Your Dream House Stand Out

Designing your dream home is an exciting journey, and for many, it’s an opportunity to create a space that reflects their personal style, functionality needs, and modern trends. ...

Client Dinners Done Right: Tips for Meaningful Engagement

Client dinners offer more than just a meal—they’re an opportunity to build lasting business relationships in a more personal and relaxed setting. Done well, these dinners can str...

From Classic to Contemporary: 5 Timeless Costumes for Any Party

When it comes to dressing up for a costume party, you want to choose something that is not only fun but also memorable. Whether you're attending a Halloween event, a themed gathe...

Action Figures as Art: The Growing Trend of Custom Figures and Modding

Action figures have long been regarded as collectible items, valued by enthusiasts and fans for their connection to popular culture. However, in recent years, a growing trend has...

The Ultimate Guide to Securing Grants for Your Small Business in Australia

Running a small business in Australia comes with both opportunities and challenges. While it can be rewarding, funding your business through the early stages or periods of growth...

Times Magazine

Top Benefits of Hiring Commercial Electricians for Your Business

When it comes to business success, there are no two ways about it: qualified professionals are critical. While many specialists are needed, commercial electricians are among the most important to have on hand. They are directly involved in upholdin...

The Essential Guide to Transforming Office Spaces for Maximum Efficiency

Why Office Fitouts MatterA well-designed office can make all the difference in productivity, employee satisfaction, and client impressions. Businesses of all sizes are investing in updated office spaces to create environments that foster collaborat...

The A/B Testing Revolution: How AI Optimized Landing Pages Without Human Input

A/B testing was always integral to the web-based marketing world. Was there a button that converted better? Marketing could pit one against the other and see which option worked better. This was always through human observation, and over time, as d...

Using Countdown Timers in Email: Do They Really Increase Conversions?

In a world that's always on, where marketers are attempting to entice a subscriber and get them to convert on the same screen with one email, the power of urgency is sometimes the essential element needed. One of the most popular ways to create urg...

Types of Software Consultants

In today's technology-driven world, businesses often seek the expertise of software consultants to navigate complex software needs. There are several types of software consultants, including solution architects, project managers, and user experienc...

CWU Assistive Tech Hub is Changing Lives: Win a Free Rollator Walker This Easter!

🌟 Mobility. Independence. Community. All in One. This Easter, the CWU Assistive Tech Hub is pleased to support the Banyule community by giving away a rollator walker. The giveaway will take place during the Macleod Village Easter Egg Hunt & Ma...

LayBy Shopping