There are some truly big men playing in the NBA. At 7’3’’, Latvian-born Kristaps Porzingis, for example, towers over the famously huge LeBron James who measures in at a massive 6’8’’. These guys would have been giants compared to Cro-Magnon Homo sapiens, who maxed out at six feet, but their physical prowess isn’t likely to be surpassed by any colossal people born in the future. According to a recent paper, we’ve reached the limits of human physicality.

A team of French scientists explain in Frontiers in Physiology explain that, though the twentieth century was an “unprecedented period” of improvement in human physiology, their analysis of 120 years of historical data reveals that we have reached our biological limits. In the study, they even suggest that some of our physical characteristics may actually be on the decline because of changing environmental conditions, like climate change.

“These traits [height, age, and physical abilities] no longer increase, despite further continuous nutritional, medical, and scientific progress,” co-author Jean-François Toussaint, Ph.D., announced in a statement.

“This suggests that modern societies have allowed our species to reach its limits. We are the first generation to become aware of this.”

 The shortest man ever, Chandra Bahadur Dangi meets the worlds tallest man, Sultan Kosen for the very first time on November 13, 2014 in London, England. 

While some studies have found that height is decreasing in the United States and Africa, this review suggests that, globally, height measurements are shifting toward the maximum heights humans have already achieved — and will likely plateau once everyone gets there. It’s reminiscent of previous studies showing that there’s an upper limit to age, as well: In these studies, data analysis showed that people are increasingly reaching the maximum ages of 115 years for men and 114 years for women but no humans are likely to surpass those numbers.

The authors of the Frontiers in Physiology review say that, in the future, we’ll see more people reach maximum life expectancy but fail to exceed, and fewer athletes will succeed in beating sports records. According to their analysis of data on Olympic athletes, records were broken by large margins between the early 1900s to the end of the 20th century but are now only broken in very small increments. Likewise, historical data on the heights of athletes also showed that there was a large leap in height during the mid-twentieth century but measurements have since plateaued in all major US sports. This is especially true in the NBA: Since 1984, the average height has remained at 6’5’’.

Blake Griffin, 6'10'', of the Los Angeles Clippers and Kristaps Porzingis, 7'3'',  of the New York Knicks.

The increases we have undergone in lifespan, height, and physical performance seem to be the result of human evolution and societal changes. Archeological evidence demonstrates that, over the last three million years, a shift towards bipedalism and running, paired with the development of our large brains, made us stronger. And, as our skeletons slowly evolved for physical activity over the last two million years, we’ve become better at skills like high-speed throwing.

For some characteristics, however, the data suggest we hit our plateau a long time ago. Studies demonstrate that men from the early Middle Ages and Americans during the Revolutionary era were about the same size as average Americans now. That’s because, ultimately, the “evolutionary restraints of body design” can’t be surpassed, even with medical technology that has helped us live increasingly longer lives.

However, there’s no guarantee we’ll even reach those upper limits, thanks to the constraints we’ve created, like climate change, poor air quality, and insect-related diseases.

“Mankind is now the major actor implicated in its own environment alterations,” the scientists write. “Sapiens alters his ecosystem, while the ecosystem also shapes him in return. Our activities have been implicated as the dominant cause of most environmental changes and the recent acceleration could have major impacts on human health.”