Humain diminué ?

Les rêves transhumanistes envisagent à court terme un homme augmenté. Mais cette humanité que l’on veut augmenter, n’est-elle pas pour l’instant une humanité diminuée, par bien des aspects ? Disons que ça peut s’argumenter…

 


Genetic contributions to variation in human stature in prehistoric Europe
Cox et al.
PNAS, 2019
https://www.pnas.org/content/pnas/116/43/21484.full.pdf

Décroissance stature paléo Cox et al. 2019

Prehistoric women’s manual labor exceeded that of athletes through the first 5500 years of farming in Central Europe
Macintosh et al.
Science advances, 2017
https://advances.sciencemag.org/content/3/11/eaao3893?_sp=511b9672-2ac6-4be2-a073-79d693da4ab4.1512048421911

Prehistoric female tibial rigidity at all time periods was highly variable, but differed little from living sedentary women on average, and was significantly lower than that of living runners and football players. However, humeral rigidity exceeded that of living athletes for the first ~5500 years of farming, with loading intensity biased heavily toward the upper limb. Interlimb strength proportions among Neolithic, Bronze Age, and Iron Age women were most similar to those of living semi-elite rowers. These results suggest that, in contrast to men, rigorous manual labor was a more important component of prehistoric women’s behavior than was terrestrial mobility through thousands of years of European agriculture, at levels far exceeding those of modern women.

The negative Flynn effect : a systematic litterature review
Dutton et al.
Intelligence, 2016
https://www.gwern.net/docs/iq/2016-dutton.pdf

The Flynn Effect (rising performance on intelligence tests in the general population over time) is now anestablished phenomenon in many developed and less developed countries. Recently, evidence has begun toamass that the Flynn Effect has gone into reverse; the so-called‘Negative Flynn Effect.’In this study, we presenta systematic literature review, conducted in order to discover in precisely how many countries this reverse phe-nomenon has been uncovered. Using strict criteria regarding quality of the sample and the study, we found ninestudies reporting negative Flynn Effects in seven countries. We also discuss several possible explanations for thenegative Flynn Effect as an attempt to understand its most probable causes.

Global prevalence of myopia and high myopia and temporal trends from 2000 through 2050
Holden et al.
American academy of ophtalmology, 2016
https://www.ncbi.nlm.nih.gov/pubmed/26875007

Myopia and high myopia estimates from 2000 to 2050 suggest significant increases in prevalences globally, with implications for planning services, including managing and preventing myopia-related ocular complications and vision loss among almost 1 billion people with high myopia.

Recent origin of low trabecular bone density in modern humans
Chirchir et al.
PNAS, 2015
https://www.pnas.org/content/112/2/366
https://www.pnas.org/content/pnas/112/2/366.full.pdf

Results show that only recent modern humans have low trabecular density throughout the limb joints. Extinct hominins, including pre-Holocene Homo sapiens, retain the high levels seen in nonhuman primates. Thus, the low trabecular density of the recent modern human skeleton evolved late in our evolutionary history, potentially resulting from increased sedentism and reliance on technological and cultural innovations.

Gradual decline in mobility with the adoption of food production in Europe
Ruff et al.
PNAS, 2015
https://www.pnas.org/content/pnas/112/23/7147.full.pdf

Together these results strongly implicate declining mobility asthe specific behavioral factor underlying these changes. Mobility levels first declined at the onset of food production, but the transition to a more sedentary lifestyle was gradual, extending through later agricultural intensification. This finding only partially supports models that tie increased sedentism to a relatively abrupt Neolithic Demographic Transition in Europe. The lack of subsequent change in relative bone strength indicates that in-creasing mechanization and urbanization had only relatively small effects on skeletal robusticity, suggesting that moderate changes in activity level are not sufficient stimuli for bone deposition or resorption.

Gradual decline in mobility, Ruff 2015

Gracility of the modern Homo sapiens skeleton is the result of decreased biomechanical loading
Timothy M. Ryana & Colin N. Shaw
PNAS, 2015
https://www.pnas.org/content/112/2/372

Analyses of mass-corrected trabecular bone variables reveal that the forager populations had significantly higher bone volume fraction, thicker trabeculae, and consequently lower relative bone surface area compared with the two agriculturalist groups. There were no significant differences between the
agriculturalist and forager populations for trabecular spacing, number,
or degree of anisotropy. These results reveal a correspondence between human behavior and bone structure in the proximal femur, indicating that more highly mobile human populations have trabecular bone structure similar to what would be expected for wild nonhuman primates of the same body mass. These results
strongly emphasize the importance of physical activity and exercise
for bone health and the attenuation of age-related bone loss.

Incongruity between Affinity Patterns Basedon Mandibular and Lower Dental Dimensionsfollowing the Transition to Agriculture in theNear East, Anatolia and Europe
Ron Pinhasi et al.
PLOS One, 2015

In the case of hunter-gatherers there is a correlation betweeninter-individual mandibular and dental distances, suggesting an equilibrium betweenthese two closely associated morphological units. However, in the case of semi-sedentaryhunter-gatherers and farming groups, no such correlation was found, suggesting that the in-congruity between dental and mandibular form began with the shift towards sedentism andagricultural subsistence practices in the core region of the Near East and Anatolia.

Were the Victorians cleverer than us? The decline in general intelligenceestimated from a meta-analysis of the slowing of simple reaction time
Michael A. Woodley et al.
Intelligence, 2013
https://lesacreduprintemps19.files.wordpress.com/2013/05/were-the-victorians-smarter-than-us.pdf

The Victorian era was marked by an explosion of innovation and genius, per capita rates of which appear to have declined subsequently. The presence of dysgenic fertility for IQ amongst Western nations, starting in the 19th century, suggests that these trends might be related to declining IQ. This is because high-IQ people are more productive and more creative. We tested the hypothesis that the Victorians were cleverer than modern populations, using high-quality instruments, namely measures of simple visual reaction time in a meta-analytic study. Simple reaction time measures correlate substantially with measures of general intelligence (g) and are considered elementary measures of cognition. In this study we used the data on the secular slowing of simple reaction time described in a meta-analysis of 14 age-matched studies from Western countries conducted between 1884 and 2004 to estimate the decline in g that may have resulted from the presence of dysgenic fertility. Using psychometric meta-analysis we computed the true correlation between simple reaction time and g, yielding a decline of −1.23 IQ points per decade or fourteen IQ points since Victorian times. These findings strongly indicate that with respect to g the Victorians were substantially cleverer than modern Western populations

Origins of Dental Crowding and Malocclusions : An Anthropological Perspective
Jerome C. Rose & Richard D. Robbly
Compendium, 2009
https://pdfs.semanticscholar.org/1322/041e2ad86a44420e857b73257af0054980aa.pdf

These analyses suggest it was not the reductionin tooth wear that increased crowding and malocclu-sion, but rather the tremendous reduction in the forcesof mastication, which produced this extreme toothwear and the subsequent reduced jaw involvement.Thus, as modern food preparation techniques spreadthroughout the world during the 19th century, so diddental crowding.

La masse moyenne des humains semble commencer à décliner avant le néolithique, laissant supposer de possibles stress ayant préludé à une modification du mode de vie.

Body mass and encephalization in Pleistocene Homo
Ruff et al.
Nature, 1997
https://www.nature.com/articles/387173a0

 

Ruff et al. 1997