We use cookies to understand how you use our site and to improve your experience. This includes personalizing content and advertising. To learn more, click here. By continuing to use our site, you accept our use of cookies. Cookie Policy.

Features Partner Sites Information LinkXpress hp
Sign In
Advertise with Us
LGC Clinical Diagnostics

Download Mobile App




First Large-Scale Quantitative Test Validates Darwin's Theory of Universal Common Ancestry

By LabMedica International staff writers
Posted on 17 Jun 2010
Print article
More than 150 years ago, Darwin proposed the theory of universal common ancestry (UCA), linking all forms of life by a shared genetic heritage from single-celled microorganisms to humans. Until now, the theory that makes all living organisms distant relatives has remained beyond the range of a formal test. Researchers have reported the findings of the first large scale, quantitative test of the famous theory that underpins modern evolutionary biology.

The results of the study confirmed that Darwin was, in fact, correct. In his 1859 book, On the Origin of Species, the British naturalist proposed that, "all the organic beings which have ever lived on this earth have descended from some one primordial form.” Over the last 150 years, qualitative evidence for this theory has grown, in the numerous, surprising transitional forms found in the fossil record, for example, and in the identification of far-reaching essential biologic similarities at the molecular level.

Still, discourse among some evolutionary biologists have recently emerged questioning whether the evolutionary relationships among living organisms are best described by a single "family tree” or rather by multiple, interconnected trees--a "web of life.” Recent molecular evidence indicates that primordial life may have undergone rampant horizontal gene transfer, which occurs frequently today when single-celled organisms swap genes using mechanisms other than usual organismal reproduction. In that case, some scientists argue, early evolutionary relationships were web-like, making it possible that life sprang up independently from many ancestors.

According to biochemist Dr. Douglas Theobald, from Brandeis University (Waltham, MA, USA), it does not really matter. "Let's say life originated independently multiple times, which UCA allows is possible,” said Dr. Theobald. "If so, the theory holds that a bottleneck occurred in evolution, with descendants of only one of the independent origins surviving until the present. Alternatively, separate populations could have merged, by exchanging enough genes over time to become a single species that eventually was ancestral to us all. Either way, all of life would still be genetically related."

Harnessing powerful computational tools and applying Bayesian statistics, Dr. Theobald found that the evidence overwhelmingly supports UCA, regardless of horizontal gene transfer or multiple origins of life. Dr. Theobald said UCA is millions of times more probable than any theory of multiple independent ancestries. "There have been major advances in biology over the last decade, with our ability to test Darwin's theory in a way never before possible,” said Dr. Theobald. "The number of genetic sequences of individual organisms doubles every three years, and our computational power is much stronger now than it was even a few years ago.”

Whereas other scientists have previously examined common ancestry more narrowly, for example, among only vertebrates, Dr. Theobald is the first to test formally Darwin's theory across all three domains of life. The three domains include diverse life forms such as the Eukarya, as well as Bacteria and Archaea.

Dr. Theobald examined a set of 23 universally conserved, basic proteins found in all known organisms. He chose to study four representative organisms from each of the three domains of life. For example, he researched the genetic links found among these proteins in archaeal microorganisms that generate marsh gas and methane in cows and the human gut; in fruit flies, humans, round worms, and baker's yeast; and in bacteria such as Escherichia coli and the pathogen that causes tuberculosis.

Dr. Theobald's study rests on several simple suppositions about how the diversity of modern proteins arose. First, he assumed that genetic copies of a protein could be multiplied during reproduction, such as when one parent gives a copy of one of their genes to several of their children. Second, he assumed that a process of replication and mutation over the eons might modify these proteins from their ancestral versions. These two factors, then, should have created the differences in the modern versions of these proteins seen throughout life today. Lastly, he assumed that genetic changes in one species do not affect mutations in another species--for example, genetic mutations in kangaroos do not affect those in humans.

What Dr. Theobald did not hypothesize, however, was how far back these processes go in linking organisms genealogically. These processes are able to link the shared proteins found in all humans to each other genetically. However, the answers to if the processes in these assumptions link humans to other animals; if these processes link animals to other eukaryotes; and if these processes link eukaryotes to the other domains of life, bacteria, and archaea turns out to be a definitive yes.

Just what did this universal common ancestor look like and where did it live? Dr. Theobald's study does not answer this question. Nevertheless, he speculated, "to us, it would most likely look like some sort of froth, perhaps living at the edge of the ocean, or deep in the ocean on a geothermal vent. At the molecular level, I'm sure it would have looked as complex and beautiful as modern life.”

The study's findings were published in the May 13, 2010, issue of the journal Nature.

Related Links:

Brandeis University



Gold Member
Serological Pipet Controller
PIPETBOY GENIUS
Verification Panels for Assay Development & QC
Seroconversion Panels
New
TETANUS Test
TETANUS VIRCLIA IgG MONOTEST
New
Bordetella Pertussis Molecular Assay
Alethia Pertussis

Print article

Channels

Clinical Chemistry

view channel
Image: The tiny clay-based materials can be customized for a range of medical applications (Photo courtesy of Angira Roy and Sam O’Keefe)

‘Brilliantly Luminous’ Nanoscale Chemical Tool to Improve Disease Detection

Thousands of commercially available glowing molecules known as fluorophores are commonly used in medical imaging, disease detection, biomarker tagging, and chemical analysis. They are also integral in... Read more

Immunology

view channel
Image: The cancer stem cell test can accurately choose more effective treatments (Photo courtesy of University of Cincinnati)

Stem Cell Test Predicts Treatment Outcome for Patients with Platinum-Resistant Ovarian Cancer

Epithelial ovarian cancer frequently responds to chemotherapy initially, but eventually, the tumor develops resistance to the therapy, leading to regrowth. This resistance is partially due to the activation... Read more

Microbiology

view channel
Image: The lab-in-tube assay could improve TB diagnoses in rural or resource-limited areas (Photo courtesy of Kenny Lass/Tulane University)

Handheld Device Delivers Low-Cost TB Results in Less Than One Hour

Tuberculosis (TB) remains the deadliest infectious disease globally, affecting an estimated 10 million people annually. In 2021, about 4.2 million TB cases went undiagnosed or unreported, mainly due to... Read more

Pathology

view channel
Image: The ready-to-use DUB enzyme assay kits accelerate routine DUB activity assays without compromising data quality (Photo courtesy of Adobe Stock)

Sensitive and Specific DUB Enzyme Assay Kits Require Minimal Setup Without Substrate Preparation

Ubiquitination and deubiquitination are two important physiological processes in the ubiquitin-proteasome system, responsible for protein degradation in cells. Deubiquitinating (DUB) enzymes contain around... Read more

Technology

view channel
Image: The HIV-1 self-testing chip will be capable of selectively detecting HIV in whole blood samples (Photo courtesy of Shutterstock)

Disposable Microchip Technology Could Selectively Detect HIV in Whole Blood Samples

As of the end of 2023, approximately 40 million people globally were living with HIV, and around 630,000 individuals died from AIDS-related illnesses that same year. Despite a substantial decline in deaths... Read more

Industry

view channel
Image: The collaboration aims to leverage Oxford Nanopore\'s sequencing platform and Cepheid\'s GeneXpert system to advance the field of sequencing for infectious diseases (Photo courtesy of Cepheid)

Cepheid and Oxford Nanopore Technologies Partner on Advancing Automated Sequencing-Based Solutions

Cepheid (Sunnyvale, CA, USA), a leading molecular diagnostics company, and Oxford Nanopore Technologies (Oxford, UK), the company behind a new generation of sequencing-based molecular analysis technologies,... Read more
Copyright © 2000-2025 Globetech Media. All rights reserved.