Written by BioLogos Fellow of Biology Dennis Venema, this series of posts is intended as a basic introduction to the science of evolution for non-specialists.
  • Evolution Basics: A New Introductory Course on Evolutionary Biology

    | Dennis Venema
    Blog Post
    Evolution Basics: A New Introductory Course on Evolutionary Biology | Dennis Venema

    The goal of this course is straightforward: to provide evangelical Christians with a step-by-step introduction to the science of evolutionary biology.  Read More >

    Basics PART 1 of 50
  • Evolution Basics: Evolution as a Scientific Theory

    | Dennis Venema
    Blog Post
    Evolution Basics: Evolution as a Scientific Theory | Dennis Venema

    In common English usage, “theory” means something like “guess” or “hunch”. It means something speculative, uncertain. In science, however, the mean... Read More >

    Basics PART 2 of 50
  • Evolution Basics: Darwin’s Early Observations on Biogeography

    | Dennis Venema
    Blog Post
    Evolution Basics: Darwin’s Early Observations on Biogeography | Dennis Venema

    These lines of evidence would later prod him to consider the possibility that species arise through a natural process of gradual change over time, rather than... Read More >

    Basics PART 3 of 50
  • Evolution Basics: New Genes, A New Diet, and Implications for Dog Origins

    | Dennis Venema
    Blog Post
    Evolution Basics: New Genes, A New Diet, and Implications for Dog Origins | Dennis Venema

    Having domesticated wolves into dogs, our selective efforts didn’t stop there, of course: humans used artificial selection to create 400-plus dog breeds, and we can see the effe... Read More >

    Basics PART 6 of 50
  • Evolution Basics: Natural Selection and the Human Lineage, Part 1

    | Dennis Venema
    Blog Post
    Evolution Basics: Natural Selection and the Human Lineage, Part 1 | Dennis Venema

    I’ve often encountered the misconception among non-biologists that mutations are always harmful, or always remove functions and information. Read More >

    Going Deeper PART 7 of 50
  • Evolution Basics: Natural Selection and the Human Lineage, Part 2

    | Dennis Venema
    Blog Post
    Evolution Basics: Natural Selection and the Human Lineage, Part 2 | Dennis Venema

    Variation, of course, is only one part of the recipe for evolutionary change. In order to shift average characteristics of a population over time, natural selection needs to be acting... Read More >

    Going Deeper PART 8 of 50
  • Evolution Basics: The Basis of Heritable Variation, Part 1

    | Dennis Venema
    Blog Post
    Evolution Basics: The Basis of Heritable Variation, Part 1 | Dennis Venema

    Taken together, the properties of DNA match what we observe in nature: faithful reproduction of form, but not perfect reproduction of form.  Read More >

    Basics PART 9 of 50
  • Evolution Basics: The Basis of Heritable Variation, Part 2

    | Dennis Venema
    Blog Post
    Evolution Basics: The Basis of Heritable Variation, Part 2 | Dennis Venema

    Taken together, these mechanisms introduce variation into populations, and since that variation is in DNA, the variation is heritable. Read More >

    Basics PART 10 of 50
  • Evolution Basics: From Variation to Speciation, Part 1

    | Dennis Venema
    Blog Post
    Evolution Basics: From Variation to Speciation, Part 1 | Dennis Venema

    …in small populations, drift can have a large impact on allele frequencies from one generation to the next. In large populations, natural selection predominates... Read More >

    Basics PART 11 of 50
  • Evolution Basics: From Variation to Speciation, Part 2

    | Dennis Venema
    Blog Post
    Evolution Basics: From Variation to Speciation, Part 2 | Dennis Venema

    Once separated from the larger population, the smaller “founding” group no longer received new alleles from it, nor passed new alleles that arose back to it. Read More >

    Basics PART 12 of 50
  • Evolution Basics: From Variation to Speciation, Part 3

    | Dennis Venema
    Blog Post
    Evolution Basics: From Variation to Speciation, Part 3 | Dennis Venema

    Once populations become spread out over a wide geographic area, the differences between the populations at the extremities...can become quite significant. Read More >

    Basics PART 13 of 50
  • Evolution basics: From Variation to Speciation, Part 4

    | Dennis Venema
    Blog Post
    Evolution basics: From Variation to Speciation, Part 4 | Dennis Venema

    For those “early” flies that were attracted to this new, but somewhat similar fruit in their environment, the result would be twofold... Read More >

    Basics PART 14 of 50
  • Evolution Basics: Genomes as Ancient Texts, Part 1

    | Dennis Venema
    Blog Post
    Evolution Basics: Genomes as Ancient Texts, Part 1 | Dennis Venema

    …while errors made by human scribes tend preserve a meaning of some kind...DNA replicating enzymes do not check to see if meaning (i.e. function) is preserved as they copy. Read More >

    Basics PART 15 of 50
  • Evolution Basics: Genomes as Ancient Texts, Part 2

    | Dennis Venema
    Blog Post
    Evolution Basics: Genomes as Ancient Texts, Part 2 | Dennis Venema

    …these observations indicate that there is no biological need for nearly identical genes at the amino acid level, or even at the DNA level, in different species. Read More >

    Basics PART 16 of 50
  • Evolution Basics: Genomes as Ancient Texts, Part 3

    | Dennis Venema
    Blog Post
    Evolution Basics: Genomes as Ancient Texts, Part 3 | Dennis Venema

    Taken together, what we observe when comparing the overall structure of the human genome to other primates is that (a) our genomes do indeed have the features one would predict... Read More >

    Basics PART 17 of 50
  • Evolution Basics: Genomes as Ancient Texts, Part 4

    | Dennis Venema
    Blog Post
    Evolution Basics: Genomes as Ancient Texts, Part 4 | Dennis Venema

    …there is no biological need for these sequences to be this identical...even for this small region of this gene, there are over 53 million different ways to code for the exact ... Read More >

    Basics PART 18 of 50
  • Evolution Basics: Genomes as Ancient Texts, Part 5

    | Dennis Venema
    Blog Post
    Evolution Basics: Genomes as Ancient Texts, Part 5 | Dennis Venema

    The longer two species have a shared history, the more similar we expect their gene sequences to be. The longer they have had a separate history, the more different we expect... Read More >

    Basics PART 18 of 50
  • Evolution Basics: Species Trees, Gene Trees and Incomplete Lineage Sorting

    | Dennis Venema
    Blog Post
    Evolution Basics: Species Trees, Gene Trees and Incomplete Lineage Sorting | Dennis Venema

    If a gene has variation in a population undergoing speciation events, it is expected that some of the time it will assort with a pattern that does not match the species pattern... Read More >

    Basics PART 20 of 50
  • Evolution Basics: Incomplete Lineage Sorting and Ancestral Population Sizes

    | Dennis Venema
    Blog Post
    Evolution Basics: Incomplete Lineage Sorting and Ancestral Population Sizes | Dennis Venema

    Discordant gene trees are a window to the past that reveal the genetic diversity of an ancestral population–how many alleles it maintained for a given region of the genome. Read More >

    Basics PART 21 of 50
  • Evolution Basics: An Introduction to Homoplasy and Convergent Evolution

    | Dennis Venema
    Blog Post
    Evolution Basics: An Introduction to Homoplasy and Convergent Evolution | Dennis Venema

    Homoplasies can be as simple as single DNA monomer changes, or as complex as the independent reorganization of multiple systems with numerous genes and body parts to converge on a sol... Read More >

    Basics PART 22 of 50
  • Evolution Basics: Convergent Evolution and Deep Homology

    | Dennis Venema
    Blog Post
    Evolution Basics: Convergent Evolution and Deep Homology | Dennis Venema

    One common misconception I encounter about evolution is that it is predominantly a random process – one that is mainly influenced by chance events.    Read More >

    Basics PART 23 of 50
  • Evolution Basics: Coevolution and Predator / Prey “Arms Races”

    | Dennis Venema
    Blog Post
    Evolution Basics: Coevolution and Predator / Prey “Arms Races” | Dennis Venema

    Moths that are merely using a warning sound to advertise their toxicity emit signals in a pattern that does not produce interference with bat echolocation... Read More >

    Basics PART 24 of 50
  • Evolution Basics: Parasitism, Mutualism and Cospeciation

    | Dennis Venema
    Blog Post
    Evolution Basics: Parasitism, Mutualism and Cospeciation | Dennis Venema

    Beyond the matching pattern of speciation, the divergence times for human and chimpanzee body lice agrees with the speciation times for their hosts. Read More >

    Basics PART 25 of 50
  • Evolution Basics: Assembling Vertebrate Body Plans, Part 1

    | Dennis Venema
    Blog Post
    Evolution Basics: Assembling Vertebrate Body Plans, Part 1 | Dennis Venema

    …the probability that any given fossil species is a direct ancestor of a modern-day species is vanishingly small. Fossilization is a highly infrequent event... Read More >

    Basics PART 29 of 50
  • Evolution Basics: Assembling Vertebrate Body Plans, Part 2

    | Dennis Venema
    Blog Post
    Evolution Basics: Assembling Vertebrate Body Plans, Part 2 | Dennis Venema

    These stem groups show us that the vertebrate body plan was assembled over time in a stepwise fashion, and that its “sudden appearance” in the Cambrian record is in fact n... Read More >

    Basics PART 30 of 50
  • Evolution Basics: Assembling Vertebrate Body Plans, Part 3

    | Dennis Venema
    Blog Post
    Evolution Basics: Assembling Vertebrate Body Plans, Part 3 | Dennis Venema

    Eusthenopteron had articulated bones in its front lobe fins – bones we recognize in modern-day tetrapods as the humerus, radius, and ulna. These are the long... Read More >

    Basics PART 31 of 50
  • Evolution Basics: Assembling Vertebrate Body Plans, Part 4

    | Dennis Venema
    Blog Post
    Evolution Basics: Assembling Vertebrate Body Plans, Part 4 | Dennis Venema

    …despite decades of protests from antievolutionists that no possible intermediate forms for birds could exist, we see a group of fossil species that meets the criteria handily.... Read More >

    Basics PART 32 of 50
  • Evolution Basics: Assembling Vertebrate Body Plans, Part 5

    | Dennis Venema
    Blog Post
    Evolution Basics: Assembling Vertebrate Body Plans, Part 5 | Dennis Venema

    At the genetic level, genes required for yolk production would eventually no longer contribute to the survival or reproduction of the organism... Read More >

    Basics PART 33 of 50
  • Evolution Basics: The Placental Revolution, Part 1

    | Dennis Venema
    Blog Post
    Evolution Basics: The Placental Revolution, Part 1 | Dennis Venema

    The placental diversification in the Paleogene is highly interesting from an evolutionary standpoint since niches that were vacated by reptiles were in many cases filled by placental.... Read More >

    Basics PART 34 of 50
  • Evolution Basics: The Placental Revolution, Part 2

    | Dennis Venema
    Blog Post
    Evolution Basics: The Placental Revolution, Part 2 | Dennis Venema

    One shared feature of haplorhine primates is their curious inability to make their own vitamin C, forcing them to acquire it from their diet. This is unusual... Read More >

    Basics PART 35 of 50
  • Evolution Basics: From Primate to Human, Part 1

    | Dennis Venema
    Blog Post
    Evolution Basics: From Primate to Human, Part 1 | Dennis Venema

    For many years, it was unclear if humans were more closely related to chimpanzees or to gorillas, but full genome sequences allowed us to resolve the issue. Read More >

    Basics PART 36 of 50
  • Evolution Basics: From Primate to Human, Part 2

    | Dennis Venema
    Blog Post
    Evolution Basics: From Primate to Human, Part 2 | Dennis Venema

    The appreciation of the hominin group as a bushy tree rather than a ladder would elude scientists for some time, to say nothing of the general public. Read More >

    Basics PART 37 of 50
  • Evolution Basics: From Primate to Human, Part 3

    | Dennis Venema
    Blog Post
    Evolution Basics: From Primate to Human, Part 3 | Dennis Venema

    The end for Piltdown would be swift in coming, and Le Gros Clark would be one of the key figures in unmasking Piltdown for what it was. Read More >

    Basics PART 38 of 50
  • Evolution Basics: From Primate to Human, Part 4

    | Dennis Venema
    Blog Post
    Evolution Basics: From Primate to Human, Part 4 | Dennis Venema

    The diversity of [hominin] remains both complicates the details of our evolution-in that we cannot be absolutely certain which (if any) of these groups are directly ancestral... Read More >

    Basics PART 39 of 50
  • Evolution and the Christian: Is Evolution a Purposeless Mechanism?

    | Dennis Venema
    Blog Post
    Evolution and the Christian: Is Evolution a Purposeless Mechanism? | Dennis Venema

    One of the primary concerns about evolution is the question of randomness, the fact that evolution appears to be an unpredictable, uncontrolled process. Read More >

    Basics PART 48 of 50