Dataset Information

An objective Bayesian analysis of life's early start and our late arrival.

ABSTRACT: Life emerged on Earth within the first quintile of its habitable window, but a technological civilization did not blossom until its last. Efforts to infer the rate of abiogenesis, based on its early emergence, are frustrated by the selection effect that if the evolution of intelligence is a slow process, then life's early start may simply be a prerequisite to our existence, rather than useful evidence for optimism. In this work, we interpret the chronology of these two events in a Bayesian framework, extending upon previous work by considering that the evolutionary timescale is itself an unknown that needs to be jointly inferred, rather than fiducially set. We further adopt an objective Bayesian approach, such that our results would be agreed upon even by those using wildly different priors for the rates of abiogenesis and evolution-common points of contention for this problem. It is then shown that the earliest microfossil evidence for life indicates that the rate of abiogenesis is at least 2.8 times more likely to be a typically rapid process, rather than a slow one. This modest limiting Bayes factor rises to 8.7 if we accept the more disputed evidence of 13C-depleted zircon deposits [E. A. Bell, P. Boehnke, T. M. Harrison, W. L. Mao, Proc. Natl. Acad. Sci. U.S.A. 112, 14518-14521 (2015)]. For intelligence evolution, it is found that a rare-intelligence scenario is slightly favored at 3:2 betting odds. Thus, if we reran Earth's clock, one should statistically favor life to frequently reemerge, but intelligence may not be as inevitable.

SUBMITTER: Kipping D

PROVIDER: S-EPMC7275750 | biostudies-literature | 2020 Jun

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

An objective Bayesian analysis of life's early start and our late arrival.

Kipping David D

Proceedings of the National Academy of Sciences of the United States of America 20200518 22

Life emerged on Earth within the first quintile of its habitable window, but a technological civilization did not blossom until its last. Efforts to infer the rate of abiogenesis, based on its early emergence, are frustrated by the selection effect that if the evolution of intelligence is a slow process, then life's early start may simply be a prerequisite to our existence, rather than useful evidence for optimism. In this work, we interpret the chronology of these two events in a Bayesian frame ...[more]

PMID: 32424083

Similar Datasets

Project description:Background:Anthropogenic changes in the climate and environment have globally affected ecological processes such that the spatiotemporal occurrence of the main annual cycle events (i.e., breeding, wintering, moulting, and migration) has shifted in migratory birds. Variation in arrival timing at migratory destinations can be proximately caused by an altered start of migration, total migration distance, and/or total speed of migration. Quantifying the relative contributions of these causes is important because this will indicate the mechanisms whereby birds could potentially adjust their annual cycle in response to global change. However, we have relatively little quantitative information about how each of these factors contributes to variation in arrival timing. My main aims are to estimate how arrival timing is correlated with variation in the start of migration and the total migration distance and how the total speed of migration may change with the total migration distance and body mass in a comprehensive analysis including multiple species. Methods:For this purpose, I considered individual tracks covering complete migrations from multiple species and distinguished between within- and between-species effects. Results:Assuming that the within- and between-species effects quantified under this approach agree with the effects acting at the individual level, starting migration one day later or increasing the total migration distance by 1000 km would result in later arrival timing by 0.4-0.8 days or 2-5 days, respectively. The generality with which the start of migration is correlated with arrival timing within species suggests that this is the general biological mechanism regulating arrival timing, rather than the total migration distance. The total speed of migration was positively correlated with the total migration distance but not with the bird's body mass. Conclusions:As the start of migration is endogenously controlled and/or affected by hatching date, directional selection can probably act on existing within-species/within-population variation to alter arrival timing. This factor and the importance of variation in the start of migration for arrival timing suggest that migratory species/populations in which there is sufficient variation in the start of migration and transgenerational processes affect the corresponding timing may present an advantage over others in coping with anthropogenic-induced global changes.

Project description:Background:When started early in pregnancy and continued up till childbirth, antenatal care (ANC) can be effective in reducing adverse pregnancy outcomes. While the proportion of women who attend ANC at least once in low income countries is high, most pregnant women attend their first ANC late. In Tanzania, while over 51% of pregnant women complete ≥4 visits, only 24% start within the first trimester. This study aimed to understand the factors that lead to delay in seeking ANC services among pregnant women in Tanzania.Methods:This qualitative descriptive case study was conducted in two rural districts in Iringa Region in Tanzania. A total of 40 focus group discussions (FGDs) were conducted involving both male and female participants in 20 villages. In addition, 36 semi-structured interviews were carried out with health care workers, members of health facility committees and community health workers. Initial findings were further validated during 10 stakeholders' meetings held at ward level in which 450 people participated. Data were analysed using thematic approach.Results:Key individual and social factors for late ANC attendance included lack of knowledge of the importance of early visiting ANC, previous birth with good outcome, traditional gender roles, fear of shame and stigma, and cultural beliefs about pregnancy. Main factors which inhibit early ANC attendance in Kilolo and Mufindi districts include spouse accompany policy, rude language of health personnel and shortage of health care providers.Conclusions:Traditional gender roles and cultural beliefs about pregnancy as well as health system factors continue to influence the timing of ANC attendance. Improving early ANC attendance, therefore, requires integrated interventions that address both community and health systems barriers. Health education on the timing and importance of early antenatal care should also be strengthened in the communities. Additionally, while spouse accompany policy is important, the implementation of this policy should not infringe women's rights to access ANC services.

Dataset Information

An objective Bayesian analysis of life's early start and our late arrival.

Publications

An objective Bayesian analysis of life's early start and our late arrival.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets