Liminal Light and Primate Evolution

2020 ◽  
Vol 49 (1) ◽  
pp. 257-276
Author(s):  
Nathaniel J. Dominy ◽  
Amanda D. Melin
Keyword(s):  
Circadian Rhythms ◽  
Fossil Record ◽  
Spectral Properties ◽  
Selective Pressure ◽  
Primate Evolution ◽  
Natural Conditions ◽  
Visual Systems ◽  
Anthropoid Primates ◽  
Diurnal Behavior ◽  
Many Sources

The adaptive origins of primates and anthropoid primates are topics of enduring interest to biological anthropologists. A convention in these discussions is to treat the light environment as binary—night is dark, day is light—and to impute corresponding selective pressure on the visual systems and behaviors of primates. In consequence, debate has tended to focus on whether a given trait can be interpreted as evidence of nocturnal or diurnal behavior in the primate fossil record. Such classification elides the variability in light, or the ways that primates internalize light in their environments. Here, we explore the liminality of light by focusing on what it is, its many sources, and its flux under natural conditions. We conclude by focusing on the intensity and spectral properties of twilight, and we review the mounting evidence of its importance as a cue that determines the onset or offset of primate activities as well as the entrainment of circadian rhythms.

scholarly journals Inhibitory interneurons of the human prefrontal cortex display conserved evolution of the phenotype and related genes

2009 ◽  
Vol 277 (1684) ◽  
pp. 1011-1020 ◽  
Author(s):  
Chet C. Sherwood ◽  
Mary Ann Raghanti ◽  
Cheryl D. Stimpson ◽  
Muhammad A. Spocter ◽  
Monica Uddin ◽  
...  
Keyword(s):  
Prefrontal Cortex ◽  
Calcium Binding ◽  
Amino Acid Level ◽  
Primate Evolution ◽  
Inhibitory Interneurons ◽  
Cognitive Domains ◽  
Inhibitory Circuitry ◽  
Show Evidence ◽  
Anthropoid Primates ◽  
And Migration

Inhibitory interneurons participate in local processing circuits, playing a central role in executive cognitive functions of the prefrontal cortex. Although humans differ from other primates in a number of cognitive domains, it is not currently known whether the interneuron system has changed in the course of primate evolution leading to our species. In this study, we examined the distribution of different interneuron subtypes in the prefrontal cortex of anthropoid primates as revealed by immunohistochemistry against the calcium-binding proteins calbindin, calretinin and parvalbumin. In addition, we tested whether genes involved in the specification, differentiation and migration of interneurons show evidence of positive selection in the evolution of humans. Our findings demonstrate that cellular distributions of interneuron subtypes in human prefrontal cortex are similar to other anthropoid primates and can be explained by general scaling rules. Furthermore, genes underlying interneuron development are highly conserved at the amino acid level in primate evolution. Taken together, these results suggest that the prefrontal cortex in humans retains a similar inhibitory circuitry to that in closely related primates, even though it performs functional operations that are unique to our species. Thus, it is likely that other significant modifications to the connectivity and molecular biology of the prefrontal cortex were overlaid on this conserved interneuron architecture in the course of human evolution.

scholarly journals ACPT gene is inactivated in mammalian lineages that lack enamel or teeth

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e10219
Author(s):  
Yuan Mu ◽  
Xin Huang ◽  
Rui Liu ◽  
Yulin Gai ◽  
Na Liang ◽  
...  
Keyword(s):  
Fossil Record ◽  
Common Ancestor ◽  
Selective Pressure ◽  
Tooth Enamel ◽  
Sperm Whale ◽  
Coding Region ◽  
Evolutionary Mechanisms ◽  
Baleen Whales ◽  
The Common ◽  
Exon 4

Loss of tooth or enamel is widespread in multiple mammal lineages. Although several studies have been reported, the evolutionary mechanisms of tooth/enamel loss are still unclear. Most previous studies have found that some tooth-related genes have been inactivated in toothless and/or enamel-less mammals, such as ENAM, ODAM, C4orf26, AMBN, AMTN, DSPP, etc. Here, we conducted evolutionary analyses on ACPT playing a key role in amelogenesis, to interrogate the mechanisms. We obtained the ACPT sequences from 116 species, including edentulous and enamel-less mammals. The results shows that variant ORF-disrupting mutations were detected in ACPT coding region among nine edentulous baleen whales and three enamel-less taxa (pygmy sperm whale, aardvark, nine-banded armadillo). Furtherly, selective pressure uncovered that the selective constraints have been relaxed among all toothless and enamel-less lineages. Moreover, our results support the hypothesis that mineralized teeth were lost or degenerated in the common ancestor of crown Mysticeti through two shared single-base sites deletion in exon 4 and 5 of ACPT among all living baleen whales. DN/dS values on transitional branches were used to estimate ACPT inactivation records. In the case of aardvark, inactivation of ACPT was estimated at ~23.60–28.32 Ma, which is earlier than oldest aardvark fossil record (Orycteropus minutus, ~19 Ma), suggesting that ACPT inactivation may result in degeneration or loss of enamel. Conversely, the inactivation time of ACPT estimated in armadillo (~10.18–11.30 Ma) is later than oldest fossil record, suggesting that inactivation of ACPT may result from degeneration or loss of enamel in these mammals. Our findings suggested that different mechanisms of degeneration of tooth/enamel might exist among toothless and enamel-less lineages during evolution. Our study further considered that ACPT is a novel gene for studying tooth evolution.

Arthropod eyes: The early Cambrian fossil record and divergent evolution of visual systems

2016 ◽  
Vol 45 (2) ◽  
pp. 152-172 ◽  
Author(s):  
Nicholas J. Strausfeld ◽  
Xiaoya Ma ◽  
Gregory D. Edgecombe ◽  
Richard A. Fortey ◽  
Michael F. Land ◽  
...  
Keyword(s):  
Fossil Record ◽  
Divergent Evolution ◽  
Early Cambrian ◽  
Visual Systems

scholarly journals A spectral refinement of the Bergelson–Host–Kra decomposition and new multiple ergodic theorems

2017 ◽  
Vol 39 (4) ◽  
pp. 1042-1070 ◽  
Author(s):  
JOEL MOREIRA ◽  
FLORIAN KARL RICHTER
Keyword(s):  
Spectral Properties ◽  
Correspondence Principle ◽  
Prime Numbers ◽  
Arithmetic Progressions ◽  
Ergodic Theorems ◽  
Ergodic Averages ◽  
Natural Conditions ◽  
Beatty Sequences ◽  
Image Position

We investigate how spectral properties of a measure-preserving system$(X,{\mathcal{B}},\unicode[STIX]{x1D707},T)$are reflected in the multiple ergodic averages arising from that system. For certain sequences$a:\mathbb{N}\rightarrow \mathbb{N}$, we provide natural conditions on the spectrum$\unicode[STIX]{x1D70E}(T)$such that, for all$f_{1},\ldots ,f_{k}\in L^{\infty }$,$$\begin{eqnarray}\lim _{N\rightarrow \infty }\frac{1}{N}\mathop{\sum }_{n=1}^{N}\mathop{\prod }_{j=1}^{k}T^{ja(n)}f_{j}=\lim _{N\rightarrow \infty }\frac{1}{N}\mathop{\sum }_{n=1}^{N}\mathop{\prod }_{j=1}^{k}T^{jn}f_{j}\end{eqnarray}$$in$L^{2}$-norm. In particular, our results apply to infinite arithmetic progressions,$a(n)=qn+r$, Beatty sequences,$a(n)=\lfloor \unicode[STIX]{x1D703}n+\unicode[STIX]{x1D6FE}\rfloor$, the sequence of squarefree numbers,$a(n)=q_{n}$, and the sequence of prime numbers,$a(n)=p_{n}$. We also obtain a new refinement of Szemerédi’s theorem via Furstenberg’s correspondence principle.

Introduction

1956 ◽  
Vol 145 (920) ◽  
pp. 291-293 ◽  
Keyword(s):  
Direct Evidence ◽  
Charles Darwin ◽  
Natural Populations ◽  
Wild Populations ◽  
Natural Conditions ◽  
Genetical Theory ◽  
To Come ◽  
Many Sources ◽  
Made In

It has seemed appropriate to hold a Discussion Meeting on this subject owing to the remarkable advances made in it during recent years. These are due principally to a realization that, in certain conditions evolution takes place in natural populations much more rapidly than had previously been suspected. Thus Major Leonard Darwin told me that he once discussed with his father the possibility of observing what we now call ‘evolution'* occurring in natural conditions. Charles Darwin said that if data were properly collected, they might reveal 'perhaps in no more than fifty years' the progress of evolutionary change. His son expressed himself as somewhat appalled at collecting data for the use only of posterity. Darwin replied that he could see no objection to this for, since astronomers often make observations which are only of value in generations to come, why should not biologists do the same? Further, the greatest work of evolutionary theory to appear this century, Sir Ronald Fisher’s Genetical theory of natural selection , published in 1930, is principally concerned with selective advantages of 1 % or less. For even a quarter of a century ago little evidence of evolution had been obtained by direct observation, while to Darwin the attempt to amass such, except as a long-term policy, seemingly appeared vain. The situation is now changed and direct evidence of evolution from the study of wild populations is beginning to accumulate from many sources. It is worth while to consider briefly to what this is due.

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