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Started by Claireliontamer, July 12, 2017, 08:18:49 PM
Quote from: Icarus on June 26, 2022, 05:10:48 AMThe tension meter used a spring or weight loaded narrow bar to push down on the fabric. The plunger with the bar was engaged with a dial indicator. The depth of depression in the fabric was translated on the indicator dial to Newtons per centimeter of tension. N/cm could be converted to pounds perinch but no one in the industry used that sort of measurement designation. It was/is strictly metric stuff. One day I may post a picture of one of my meters.
Quote from: Icarus on June 30, 2022, 11:31:18 PMBack to brains.........Recent studies report that parts of the human brain have higher temperatures than any other parts of the body. Temps in the 105 F range are reported. Those temps are variable and present in all of us. Females show about three quarters of a degree higher temps than males. The temperatures vary throughout the day and during sleep. That gives new meaning to expressions like hot head.
QuoteMany believe our particularly large brain is what makes us human – but is there more to it? The brain's shape, as well as the shapes of its component parts (lobes) may also be important.Results of a study we published today in Nature Ecology & Evolution show that the way the different parts of the human brain evolved separates us from our primate relatives. In a sense, our brains never grow up. We share this "Peter Pan syndrome" with only one other primate – the Neanderthals.Our findings provide insight into what makes us human, but also further narrow any distinction between ourselves and our extinct, heavy-browed cousins.Mammalian brains have four distinct regions or lobes, each with particular functions. The frontal lobe is associated with reasoning and abstract thought, the temporal lobe with preserving memory, the occipital lobe with vision, and the parietal lobe helps to integrate sensory inputs.We investigated whether the brain's lobes evolved independently of each other, or whether evolutionary change in any one lobe appears to be necessarily tied to changes in others – that is, evidence the evolution of the lobes is "integrated".In particular, we wanted to know how human brains might differ from other primates in this respect.One way to address this question is to look at how the different lobes have changed over time among different species, measuring how much shape change in each lobe correlates with shape change in others.Alternatively, we can measure the degree to which the brain's lobes are integrated with each other as an animal grows through different stages of its life cycle.[. . .]The results of our analyses surprised us. Tracking change over deep time across dozens of primate species, we found humans had particularly high levels of brain integration, especially between the parietal and frontal lobes.But we also found we're not unique. Integration between these lobes was similarly high in Neanderthals too.Looking at changes in shape through growth revealed that in apes, such as the chimpanzee, integration between the brain's lobes is comparable to that of humans until they reach adolescence.At this point, integration rapidly falls away in the apes, but continues well into adulthood in humans.[Continues . . .]
QuoteAbstract:There is controversy around the mechanisms that guided the change in brain shape during the evolution of modern humans. It has long been held that different cortical areas evolved independently from each other to develop their unique functional specializations. However, some recent studies suggest that high integration between different cortical areas could facilitate the emergence of equally extreme, highly specialized brain functions. Here, we analyse the evolution of brain shape in primates using three-dimensional geometric morphometrics of endocasts. We aim to determine, firstly, whether modern humans present unique developmental patterns of covariation between brain cortical areas; and secondly, whether hominins experienced unusually high rates of evolution in brain covariation as compared to other primates. On the basis of analyses including modern humans and other extant great apes at different developmental stages, we first demonstrate that, unlike our closest living relatives, Homo sapiens retain high levels of covariation between cortical areas into adulthood. Among the other great apes, high levels of covariation are only found in immature individuals. Secondly, at the macro-evolutionary level, our analysis of 400 endocasts, representing 148 extant primate species and 6 fossil hominins, shows that strong covariation between different areas of the brain in H. sapiens and Homo neanderthalensis evolved under distinctly higher evolutionary rates than in any other primate, suggesting that natural selection favoured a greatly integrated brain in both species. These results hold when extinct species are excluded and allometric effects are accounted for. Our findings demonstrate that high covariation in the brain may have played a critical role in the evolution of unique cognitive capacities and complex behaviours in both modern humans and Neanderthals.