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Psouni, Elia
Publications (2 of 2) Show all publications
Psouni, E., Janke, A. & Garwicz, M. (2012). Impact of carnivory on human development and evolution revealed by a new unifying model of weaning in mammals. PLoS ONE, 7(4), e32452
Open this publication in new window or tab >>Impact of carnivory on human development and evolution revealed by a new unifying model of weaning in mammals
2012 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, no 4, p. e32452-Article in journal (Refereed) Published
Abstract [en]

Our large brain, long life span and high fertility are key elements of human evolutionary success and are often thought to have evolved in interplay with tool use, carnivory and hunting. However, the specific impact of carnivory on human evolution, life history and development remains controversial. Here we show in quantitative terms that dietary profile is a key factor influencing time to weaning across a wide taxonomic range of mammals, including humans. In a model encompassing a total of 67 species and genera from 12 mammalian orders, adult brain mass and two dichotomous variables reflecting species differences regarding limb biomechanics and dietary profile, accounted for 75.5%, 10.3% and 3.4% of variance in time to weaning, respectively, together capturing 89.2% of total variance. Crucially, carnivory predicted the time point of early weaning in humans with remarkable precision, yielding a prediction error of less than 5% with a sample of forty-six human natural fertility societies as reference. Hence, carnivory appears to provide both a necessary and sufficient explanation as to why humans wean so much earlier than the great apes. While early weaning is regarded as essentially differentiating the genus <italic>Homo</italic> from the great apes, its timing seems to be determined by the same limited set of factors in humans as in mammals in general, despite some 90 million years of evolution. Our analysis emphasizes the high degree of similarity of relative time scales in mammalian development and life history across 67 genera from 12 mammalian orders and shows that the impact of carnivory on time to weaning in humans is quantifiable, and critical. Since early weaning yields shorter interbirth intervals and higher rates of reproduction, with profound effects on population dynamics, our findings highlight the emergence of carnivory as a process fundamentally determining human evolution.

National Category
Psychology
Identifiers
urn:nbn:se:hkr:diva-9252 (URN)10.1371/journal.pone.0032452 (DOI)000305350600003 ()22536316 (PubMedID)
Available from: 2012-05-08 Created: 2012-05-02 Last updated: 2017-12-07Bibliographically approved
Thelin, J., Jörntell, H., Psouni, E., Garwicz, M., Schouenborg, J., Danielsen, N. & Eriksson Linsmeier, C. (2011). Implant size and fixation mode strongly influence tissue reactions in the CNS. PLoS ONE, 6(1), e16267
Open this publication in new window or tab >>Implant size and fixation mode strongly influence tissue reactions in the CNS
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2011 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 6, no 1, p. e16267-Article in journal (Refereed) Published
Abstract [en]

The function of chronic brain machine interfaces depends on stable electrical contact between neurons and electrodes. A key step in the development of interfaces is therefore to identify implant configurations that minimize adverse long-term tissue reactions. To this end, we here characterized the separate and combined effects of implant size and fixation mode at 6 and 12 weeks post implantation in rat (n = 24) cerebral cortex. Neurons and activated microglia and astrocytes were visualized using NeuN, ED1 and GFAP immunofluorescence microscopy, respectively. The contributions of individual experimental variables to the tissue response were quantified. Implants tethered to the skull caused larger tissue reactions than un-tethered implants. Small diameter (50 mu m) implants elicited smaller tissue reactions and resulted in the survival of larger numbers of neurons than did large diameter (200 mu m) implants. In addition, tethering resulted in an oval-shaped cavity, with a cross-section area larger than that of the implant itself, and in marked changes in morphology and organization of neurons in the region closest to the tissue interface. Most importantly, for implants that were both large diameter and tethered, glia activation was still ongoing 12 weeks after implantation, as indicated by an increase in GFAP staining between week 6 and 12, while this pattern was not observed for un-tethered, small diameter implants. Our findings therefore clearly indicate that the combined small diameter, un-tethered implants cause the smallest tissue reactions.

Keywords
intracortical electrode array, silicon microelectrode arrays, rodent, somatosensory cortex, deep brain-stimulation, rat, biocompatibility, capability, interfaces, multisite, titanium
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:hkr:diva-8785 (URN)10.1371/journal.pone.0016267 (DOI)000286662800022 ()21298109 (PubMedID)
Available from: 2011-12-07 Created: 2011-12-06 Last updated: 2017-12-08Bibliographically approved
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