For homo sapiens, it's all downhill from here. Or, at best, a plateau.
That's the conclusion of a new review article by nine French scientists. They conclude that, in terms of physical capability and performance, our species has reached its peak. The challenge will be not falling backwards.
"It is now possible to ascertain the biological limits of the human species, through sports records, lifespan, or height," a research team led by Adrien Marck writes in the journal Frontiers in Physics. "These traits no longer increase, despite further continuous nutritional, medical, and scientific progress. This suggests modern societies have allowed our species to reach its limits."
Marck and his colleagues analyzed data spanning 120 years on physiology, evolution, and the environment. The data included trends in average human height and lifespan, as well as athletic records.
They report that such records were regularly shattered during the 20th century. The best score for the 100-meter free-style swim was 65 seconds in 1905, but 49.9 seconds in 2009.
However, their data shows "a common slow-down" in the both the number of records that are broken, and the amount by which they are shattered. This suggests "a trend toward a plateau during the last three decades for both sexes," they write.
If the elite have reached their peak, the rest of us seem to be backsliding.
"Long historical series in Western Europe or Scandinavian countries show a decline in endurance and strength performance of young men," the researchers write. "Studies indicate that fewer individuals reach excellent physical performance while more and more subjects remain at low physical performance levels."
Whew. Excuse me for a second—all this typing is wearing me out.
Their analysis of human lifespan showed a similar trend. While there was "unprecedented progression during the 20th century," they write, "recent data suggest a slowdown in the progress of life expectancy."
While debate on this point continues to rage, they conclude that proposed interventions to extend our lives are unlikely to work, in that "human beings are already extremely 'optimized' for lifespan."
So are we out of challenges? Not at all, the researchers argue. In fact, they offer two: setting policies that ensure a greater percentage of the population will achieve its maximum physical potential, and making sure we don't regress as a species.
"The added pressure from anthropogenic activities (that is to say, pollution) will be responsible for damaging effects on human health and the environment," said Jean-Francois Toussaint of Paris Descartes University, the study's senior author. "[These findings] are a sign that environmental changes, including climate, are already contributing to the increasing constraints we now have to consider."
In other words, considering the damage we are doing to our environment, holding our own may be a significant achievement.