Evolution: quotes, facts and reflections - Page 2

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Cards are connected by subject and by mood. Move through the complete sequence below, or cross into a neighbouring part of the archive.

11Drive

12Stillness

35Wonder

Q1829

WonderOcean

Certain sacoglossan sea slugs retain functional chloroplasts taken from algae, using the stolen organelles for photosynthesis for days or even months.

The slug digests an alga but spares its chloroplasts, lodging them in cells along the gut. There, organelles built to work inside another organism continue harvesting light despite losing the algal nucleus that normally supports them. Kleptoplasty blurs feeding and partnership: a meal becomes temporary anatomy, and captured machinery keeps earning energy after its owner is gone.

KleptoplastyRead card

Q1830

WonderBiology

Choanoflagellates are the closest living unicellular relatives of animals, offering clues to the cell biology from which animal multicellularity evolved.

Choanoflagellates are not our ancestors; they are a surviving sister lineage. Their whip-like flagellum draws water through a collar of microvilli, and their genes include components later used in animal adhesion and signalling. Studying them turns origins into comparison: not a missing link, but a living neighbour preserving alternate uses for ancient cellular tools.

ChoanoflagellateRead card

Q1833

WonderOcean

Crocodile icefish are the only known vertebrates without functional haemoglobin in adulthood, surviving in oxygen-rich polar water with major circulatory adaptations.

Cold seawater holds more dissolved oxygen, but losing haemoglobin is still an extreme evolutionary gamble. Icefish compensate with large hearts, wide blood vessels, high blood volume and scaleless skin that can assist gas exchange. Their success is exquisitely local: a body redesigned around a cold, oxygenated ocean that climate change is now altering.

ChannichthyidaeRead card

Q1835

WonderOcean

A siphonophore colony begins as one fertilized egg; genetically identical zooids later bud from it and specialize in movement, feeding, defence or reproduction.

One larva develops from a fertilized egg, then produces zooids by budding as the colony grows. Each genetically identical unit follows a different developmental path and may be unable to survive alone: some propel, some sting and capture prey, some digest and some reproduce. The result unsettles the border between individual and collective—a single origin elaborated into animal units that function like organs.

SiphonophoraeRead card

Q1836

WonderOcean

When attacked, hagfish release mucus and microscopic protein threads that expand through seawater into extraordinary volumes of defensive slime.

The hagfish does not carry a tank of finished gel. It releases concentrated mucin and skeins of coiled protein, which seawater rapidly pulls apart into a fibrous network capable of clogging a predator's gills. The animal then ties its flexible body into a knot to scrape itself clean: chemistry deploys the shield, movement removes it.

HagfishRead card

Q1851

WonderEvolution

Marine three-spined sticklebacks repeatedly colonized fresh water and evolved reduced armour, often drawing on ancient genetic variants already present at low frequency.

After glaciers retreated, ocean fish entered newly formed lakes and streams. In many places, heavy plates became costly and diminished along strikingly similar genetic routes. The raw material was often standing variation carried by marine populations, showing that rapid adaptation can begin not with a fresh mutation, but with an old possibility waiting for a new environment.

Three-spined sticklebackRead card

Q1852

WonderEvolution

Hawaiian silverswords, shrubs, cushion plants, vines and trees evolved from one colonizing tarweed lineage, an extraordinary morphological range across the islands' habitats.

An ancestor related to North American tarweeds reached remote Hawaii and met ecological opportunities with few close competitors. Its descendants stretched one lineage into ground-hugging mats, woody shrubs, vines and trees, including Haleakalā's reflective silverswords. The spectacle is botanical engineering across altitude: bark, water-storing tissue, cushions and silver leaves assembled from shared ancestry.

Silversword allianceRead card

Q1853

WonderEvolution

Hybridization between cichlid lineages mixed genetic variation that selection could reshape into specialized jaws, feeding strategies, colours and habitats across Africa's Great Lakes.

When formerly separated lineages met, their genomes could recombine variants shaped by different histories. That mixed inheritance gave selection new combinations as cichlids split ecological work: scraping algae, crushing shells, hunting fish or feeding in open water. Their rapidly remodelled jaws make diversity tangible. In these radiations, exchange between lineages was not noise around evolution; it helped furnish its raw material.

CichlidRead card

Q1854

WonderEvolution

Separate cave populations of the Mexican tetra repeatedly evolved reduced eyes and pigmentation, providing natural replicates of adaptation to permanent darkness.

Surface and cave forms belong to the same species, and more than thirty cave populations offer repeated versions of a similar challenge. Eyes and pigment diminish while smell, taste, vibration sensing and metabolism change, but the genetic routes can differ between caves. Convergence produces a familiar destination without requiring one prescribed road.

Mexican tetraRead card

Q1855

WonderEvolution

Polyploidy duplicates whole chromosome sets, and repeated whole-genome duplications have supplied plant lineages with redundancy that can enable divergence, novelty and speciation.

A duplicated genome creates immediate complications: pairing chromosomes, balancing expression and reproducing successfully. Yet it also creates spare gene copies that can divide old work or acquire new functions, and it can isolate a lineage from its diploid relatives. Duplication is not automatic progress; it is a risky surplus from which evolution sometimes makes room to experiment.

PolyploidyRead card

Q1859

WonderArchaeology

The Schöningen finds include carefully balanced wooden hunting weapons; form and experiments indicate that at least some were capable of effective flight, while their precise age remains under review.

Waterlogged deposits at Schöningen preserved wooden objects that normally vanish from deep prehistory. Craftspeople selected trunks, controlled taper and balance, and used the weapons in a landscape rich with horse remains. New dating work continues to refine when the assemblage was made; the durable conclusion is technological sophistication, not one immutable number.

Schöningen spearsRead card