Trinkaus E, Holliday TW, Auerbach BM (March 2014). "Neandertal clavicle length". Proceedings of the National Academy of Sciences of the United States of America. 111 (12): 4438–4442. Bibcode: 2014PNAS..111.4438T. doi: 10.1073/pnas.1402439111. PMC 3970543. PMID 24616525. Levantine Neanderthals had phenotypes significantly more similar to modern humans than European Neanderthals (classic Neanderthals). [25] [26] This may be because of gene flow from early modern humans in the Levantine corridor or the fact that the European Neanderthal phenotype is a specialized climatic adaptation. Bogin B (1997). "Evolutionary hypotheses for human childhood". American Journal of Physical Anthropology. 104 (S25): 63–89. doi: 10.1002/(SICI)1096-8644(1997)25+<63::AID-AJPA3>3.0.CO;2-8. hdl: 2027.42/37682. S2CID 12791423.

But cavemen weren't watching their calories; they just didn't have access to the huge quantities of sugar available today. Modern technology allows humans to extract sugar from a wide range of sources — including sugar cane, maple trees, beehives and corn stalks — and ship that sugar around the world in huge quantities and at unprecedented speeds.

But a habit that modern people might view as lazy would have been considered smart by humanity's ancestors: Hunting and gathering was energy-intensive, and short breaks of inactivity offered the rare chance to save hard-earned calories. Two non-specific indicators of stress during development are found in teeth, which record stresses, such as periods of food scarcity or illness, that disrupt normal dental growth. One indicator is enamel hypoplasia, which appears as pits, grooves, or lines in the hard enamel covering of teeth. The other indicator, fluctuating asymmetry, manifests as random departures from symmetry in paired biological structures (such as right and left teeth). Teeth do not grow in size after they form nor do they produce new enamel, so enamel hypoplasia and fluctuating asymmetry provide a permanent record of developmental stresses occurring in infancy and childhood. A study of 669 Neanderthal crowns showed that 75% of individuals suffered some degree of hypoplasia. Two studies, [32] [33] compared Neanderthals with the Tigara, coastal whale-hunting people from Point Hope Alaska, finding comparable levels of linear enamel hypoplasia (a specific form of hypoplasia) and higher levels of fluctuating asymmetry in Neanderthals. [ non-primary source needed] Estimated stress episode duration from Neanderthal linear enamel hyoplasias suggest that Neandertals experienced stresses lasting from two weeks to up to three months. [ citation needed] Infection [ edit ] But after running into a few challenges on their own adventures, the pair decided to join their local “grotto”, a more formally organized chapter of the National Speleological Society, which started in the 1960s, long before technology like GPS.

Gómez-Olivencia A, Barash A, García-Martínez D, Arlegi M, Kramer P, Bastir M, Been E (October 2018). "3D virtual reconstruction of the Kebara 2 Neandertal thorax". Nature Communications. 9 (1): 4387. Bibcode: 2018NatCo...9.4387G. doi: 10.1038/s41467-018-06803-z. PMC 6207772. PMID 30377294. Berger TD, Trinkaus E (November 1995). "Patterns of trauma among Neadertals". Journal of Archaeological Science. 22 (6): 841–852. doi: 10.1016/0305-4403(95)90013-6. a b c Bailey SE (June 2002). "A closer look at Neanderthal postcanine dental morphology: the mandibular dentition". The Anatomical Record. 269 (3): 148–156. doi: 10.1002/ar.10116. PMID 12124901. S2CID 23593533. Helmuth, H. (1998). "Body height, body mass and surface area of the Neandertals". Zeitschrift für Morphologie und Anthropologie. 82 (1): 1–12. ISSN 0044-314X. JSTOR 25757530.Helmuth H (1998). "Body height, body mass and surface area of the Neanderthals". Zeitschrift für Morphologie und Anthropologie. 82 (1): 1–12. doi: 10.1127/zma/82/1998/1. PMID 9850627.