Humans may have reached their peak - and could soon start moving backward, a chilling new report has warned.
Experts analysed 120 years worth of historical information, and concluded maximum limits for height, lifespan and physical performance have been met.
In fact, they warn human impacts on the environment - including climate change - could mean we will soon never reach these limits again, according to the Daily Mail.
Published in Frontiers in Physiology, the review is the first of its kind spanning 120 years worth of historical information, while considering the effects of both genetic and environmental parameters.
It concluded there may be a maximum threshold to our biological limits that we cannot exceed.
"These traits no longer increase, despite further continuous nutritional, medical, and scientific progress,' said Professor Jean-François Toussaint from Paris Descartes University, France.
"This suggests that modern societies have allowed our species to reach its limits.
"We are the first generation to become aware of this.
"Rather than continually improving, we will see a shift in the proportion of the population reaching the previously recorded maximum limits."
The team say examples of the effects of these plateaus will be seen as fewer sporting records are broken and more people reach but don't exceed the present highest life expectancy.
When researchers considered how environmental and genetic limitations combined may affect the ability for us to reach these upper limits, our effect on the environment was found to play a key role.
"This will be one of the biggest challenges of this century as the added pressure from anthropogenic activities will be responsible for damaging effects on human health and the environment," Toussaint said.
"The current declines in human capacities we can see today are a sign that environmental changes, including climate, are already contributing to the increasing constraints we now have to consider.
"Observing decreasing tendencies may provide an early signal that something has changed but not for the better.
"Human height has decreased in the last decade in some African countries; this suggests some societies are no longer able to provide sufficient nutrition for each of their children and maintain the health of their younger inhabitants," Toussaint explains.
What can be done?
To avoid us being the cause of our own decline, the researchers say they hope their findings will encourage policymakers to focus on strategies for increasing quality of life and maximise the proportion of the population that can reach these maximum biological limits.
"Now that we know the limits of the human species, this can act as a clear goal for nations to ensure that human capacities reach their highest possible values for most of the population,' said Toussaint.
"With escalating environmental constraints, this may cost increasingly more energy and investment in order to balance the rising ecosystem pressures.
"However, if successful, we then should observe an incremental rise in mean values of height, lifespan and most human biomarkers.'"
Toussaint warns, "The utmost challenge is now to maintain these indices at high levels."