• HOME
  • NEWS
  • EXPLORE
    • CAREER
      • Companies
      • Jobs
    • EVENTS
    • iGEM
      • News
      • Team
    • PHOTOS
    • VIDEO
    • WIKI
  • BLOG
  • COMMUNITY
    • FACEBOOK
    • INSTAGRAM
    • TWITTER
Wednesday, September 3, 2025
BIOENGINEER.ORG
No Result
View All Result
  • Login
  • HOME
  • NEWS
  • EXPLORE
    • CAREER
      • Companies
      • Jobs
        • Lecturer
        • PhD Studentship
        • Postdoc
        • Research Assistant
    • EVENTS
    • iGEM
      • News
      • Team
    • PHOTOS
    • VIDEO
    • WIKI
  • BLOG
  • COMMUNITY
    • FACEBOOK
    • INSTAGRAM
    • TWITTER
  • HOME
  • NEWS
  • EXPLORE
    • CAREER
      • Companies
      • Jobs
        • Lecturer
        • PhD Studentship
        • Postdoc
        • Research Assistant
    • EVENTS
    • iGEM
      • News
      • Team
    • PHOTOS
    • VIDEO
    • WIKI
  • BLOG
  • COMMUNITY
    • FACEBOOK
    • INSTAGRAM
    • TWITTER
No Result
View All Result
Bioengineer.org
No Result
View All Result
Home NEWS Science News Biology

The toes tell the tale

Bioengineer by Bioengineer
August 23, 2017
in Biology
Reading Time: 3 mins read
0
Share on FacebookShare on TwitterShare on LinkedinShare on RedditShare on Telegram

If you want to understand the history of modern horses, start with their toes.

With just one toe per foot, horses are something of an outlier in the animal kingdom, but it wasn't always that way. As hard as it may be to imagine, their earliest ancestors were typically about the size of a small dog, and sported three toes on their front legs, and four on the back.

Harvard scientists are shedding new light on what drove those changes, and in a new study show that the dual pressures of increasing body weight and shrinking side toes prompted early horses' middle toes to become dramatically stronger and better able to resist forces. The study is described in an August 23 paper published in Proceedings of the Royal Society B.

"The story told in most textbooks and museums is that as grasslands gradually took over from forests, horses got bigger, and they reduced their toes to a single digit," said first author Brianna McHorse, a Ph.D. student working in the labs of Assistant Professor Stephanie Pierce and Professor Andrew Biewener in the Department of Organismic and Evolutionary Biology.

Selective pressures from new open terrain are hypothesized to drive these changes in digit reduction and body mass – but what are the underlying mechanical consequences of standing on one toe? When in horse evolution did their side toes become non-functional?

To quantitatively test these questions, the team performed micro-CT scans of 12 fossil horse species then used engineering "beam bending" analysis to calculate how much stress each species' lower leg bones were experiencing during normal movement and high-speed running. The stress data were then compared to the fracture stress of bone.

"We assessed bone stress in two ways – the first was to assume a body weight load on the center digit, which is consistent with what living horses experience, but this ignores the potential load-bearing capacity of the side toes of earlier horses," McHorse said. "The second thing we did was to scale that load relative to the size of the side toes, so the larger those toes were, the more load they take off the center digit."

The results, she said, showed that, for many early horse species, those side toes played a critical role, helping to bear some of the animal's weight to avoid unsafe levels of stress – and potential bone fracture – on their middle digit.

But as horses continued to evolve larger body sizes things began to change.

"As body mass increased, and side toes shrunk, the middle digit compensated by changing its internal geometry, allowing ever-bigger horse species to eventually stand and move on one toe," Pierce said. "The bone within the load-bearing digit of later horses was distributed farther away from the center of its cross-section, allowing it to better resist bending. The total amount of bone also increased, allowing it to better resist compression as well as bending, which are of critical importance for animals with large body sizes."

Ultimately, the team said, the study offers the clearest story yet of not only how, but why, horses took a common evolutionary theme like digit reduction and – literally – ran with it.

"Digit reduction is a repeated theme throughout evolution, but going all the way to a single toe…is an uncommon strategy, and in fact horses are the only living monodactyl [single-toed] animal," McHorse said. "[Despite that,] horses can do some pretty high-performance things – they can run at high speed, jump, and dodge sideways very quickly, and properly trained, they can cover 100 miles in a day. And plenty of people don't realize they do it all on one toe."

###

Media Contact

Peter Reuell
[email protected]
617-496-8070
@HarvardResearch

http://www.harvard.edu

Share14Tweet7Share2ShareShareShare1

Related Posts

Streamlined Hybrid Capture Enhances Specificity, Eliminates PCR

September 2, 2025

DNA Reveals Diet and Prey of Wolves and Lynx

September 2, 2025

Rice Researchers Pioneer Engineering of Computing Systems Using Living Cells

September 2, 2025

Scientists Reveal Link Between Gut Fungi, Human Genetics, and Disease Susceptibility

September 2, 2025
Please login to join discussion

POPULAR NEWS

  • Needlestick Injury Rates in Nurses and Students in Pakistan

    296 shares
    Share 118 Tweet 74
  • Breakthrough in Computer Hardware Advances Solves Complex Optimization Challenges

    154 shares
    Share 62 Tweet 39
  • Molecules in Focus: Capturing the Timeless Dance of Particles

    143 shares
    Share 57 Tweet 36
  • New Drug Formulation Transforms Intravenous Treatments into Rapid Injections

    117 shares
    Share 47 Tweet 29

About

We bring you the latest biotechnology news from best research centers and universities around the world. Check our website.

Follow us

Recent News

KIF13B Protein Regulates Liver Metabolism, Combats Fatty Liver

Transforming Date Palm Waste into Probiotic Yogurt Enhancements

Tech-Enhanced Nursing Strategies Boost TB Medication Adherence

  • Contact Us

Bioengineer.org © Copyright 2023 All Rights Reserved.

Welcome Back!

Login to your account below

Forgotten Password?

Retrieve your password

Please enter your username or email address to reset your password.

Log In
No Result
View All Result
  • Homepages
    • Home Page 1
    • Home Page 2
  • News
  • National
  • Business
  • Health
  • Lifestyle
  • Science

Bioengineer.org © Copyright 2023 All Rights Reserved.