Related Experiment Video
Updated: Aug 5, 2026
10:00
Measurement of Lifespan in Drosophila melanogaster
Published on: January 7, 2013
Survivorship Bias Explains Age-Dependent Extinction in Fossil Genera
Mikhail Tikhonov1,2, Kim Sneppen3, Stefan Bornholdt4,5
1Department of Physics, Washington University in St. Louis, St Louis, MO, USA.
Biorxiv : the Preprint Server for Biology
|August 1, 2026
Summary
Fossil genera extinction patterns can be explained by survivorship bias alone. Older genera are not inherently more resistant to extinction; rather, vulnerable genera are eliminated over time, leaving a more robust surviving pool.
Area of Science:
- Paleontology
- Evolutionary Biology
- Statistical Modeling
Background:
- Fossil records show older genera have higher survival rates during extinction events.
- Proposed biological mechanisms suggest lineages gain extinction resistance over time.
- Survivorship bias offers an alternative explanation: elimination of weaker lineages.
Purpose of the Study:
- To test if survivorship bias alone can explain age-dependent extinction patterns.
- To develop a quantitative model based solely on survivorship bias.
- To determine if explicit age-dependent changes in lineage properties are necessary.
Main Methods:
- Utilized the Sepkoski marine genus compendium.
- Constructed a quantitative model incorporating only survivorship bias.
- Fitted the model using a single parameter.
Main Results:
- The survivorship bias model accurately reproduced age-conditioned survival probabilities.
- The model quantitatively explained extinction risk dependence on genus age.
- No significant improvement was observed when allowing for systematic changes in extinction resistance over time.
Conclusions:
- Survivorship bias is sufficient to explain aggregate age-dependent extinction patterns in the fossil record.
- Explicit age-dependent changes in lineage properties are not required at the statistical level.
- The developed one-parameter model serves as a quantitative null model for extinction research.
Related Concept Videos
01:29Life Histories
Constrained by limited energy and resources, organisms must compromise between offspring quantity and parental investment. This trade-off is represented by two primary reproductive strategies; K-strategists produce few offspring but provide substantial parental support, whereas r-strategists produce much progeny that receives little care. These strategies are related to an organism’s survival likelihood across its lifespan, which is represented by a survivorship curve. Three general types of...
02:56The Fossil Record
The fossil record documents only a small fraction of all organisms that have ever inhabited Earth. Fossilization is a rare process, and most organisms never become fossils. Moreover, the fossil record only exhibits fossils that have been discovered. Nevertheless, sedimentary rock fossils of long-lived, abundant, hard-bodied organisms dominate the fossil record. These fossils offer valuable information, such as an organism's physical form, behavior, and age. Studying the fossil record helps...
02:55The Evidence for Evolution
Genetic variations accumulating within populations over generations give rise to biological evolution. Evolutionary changes can result in the formation of novel varieties and entire new species. These changes are responsible for the diverse forms of life inhabiting the planet. The evidence for evolution suggests that all living organisms descended from common ancestors.The collection of fossils within sedimentary rocks give a record of common ancestry and often depicts the history of evolution.
02:07Conservation of Declining Populations
Conservation of declining population focuses on ways of detecting, diagnosing, and halting a population decline. The approach uses methods to prevent populations from going extinct.
01:07Speciation Rates
Speciation can proceed at markedly different rates, and evolutionary biologists commonly describe these differences through the models of gradualism and punctuated equilibrium. Both patterns explain how new species arise, but they differ in the tempo and continuity of evolutionary change. In both cases, evolutionary change arises from heritable variation within populations, with natural selection often shaping traits that improve survival and reproduction under specific environmental conditions.
02:04Conservation of Small Populations
Small population sizes put a species at extreme risk of extinction due to a lack of variation, and a consequent decrease in adaptability. This weakens the chances of survival under pressures such as climate change, competition from other species, or new diseases. Large populations are more likely to survive pressures such as these, as such populations are more likely to harbor individuals that have genetic variants that are adaptive under new stresses. Small populations are much less likely to...