---
title: "Evidence of Evolution"
book: "Primary & Middle School Biology"
subject: biology
language: en
chapter: 67
exercises: 12
source: https://one-course.com/books/biology/1/en/chapter/67-evidence-of-evolution
---

# Chapter 67 — Evidence of Evolution

Twice this book has stopped at the edge of a great claim: the [kinship](https://one-course.com/books/biology/1/en/chapter/44-classification-and-kinship#prop-g6-classification-kinship-kinship) tree’s [branches](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-tree) all meet ([Remark 44.8](https://one-course.com/books/biology/1/en/chapter/44-classification-and-kinship#rem-g6-classification-kinship-implies)), and every [living thing](https://one-course.com/books/biology/1/en/chapter/37-exploring-our-environment#def-g6-exploring-our-environment-components) reads one code ([Remark 65.7](https://one-course.com/books/biology/1/en/chapter/65-genes-and-dna#rem-g9-genes-and-dna-universal)). The claim they point to has a name — *evolution*: [species](https://one-course.com/books/biology/1/en/chapter/30-biodiversity#def-g5-biodiversity-species) change across generations, and all descend from common ancestors. Before the next chapter asks *how*, this one does what [Exercise 44.12](https://one-course.com/books/biology/1/en/chapter/44-classification-and-kinship#exo-g6-classification-kinship-12) demanded: it lays out the evidence.

## 67.1 The witness of the rocks

**Definition 67.1 (Fossils).**

A *fossil* is a preserved trace of past life — [shell](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-covering), [bone](https://one-course.com/books/biology/1/en/chapter/17-bones-and-muscles#def-g3-bones-and-muscles-skeleton), leaf-print, footprint — sealed in sedimentary rock. Rock layers stack in time order, oldest lowest; reading upward reads history. Fossils are the remains half of [Definition 37.1](https://one-course.com/books/biology/1/en/chapter/37-exploring-our-environment#def-g6-exploring-our-environment-components)’s inventory, kept for millions of years.

**Proposition 67.2 (What the layered record shows).**

Read in order, the record testifies three times:

1. *faunas change* : each layer-age holds its own cast — no rabbits among the trilobites, no trilobites in the rabbit layers; most [species](https://one-course.com/books/biology/1/en/chapter/30-biodiversity#def-g5-biodiversity-species) of every deep layer are *[extinct](https://one-course.com/books/biology/1/en/chapter/30-biodiversity#prop-g5-biodiversity-loss)* ( [Proposition 30.8](https://one-course.com/books/biology/1/en/chapter/30-biodiversity#prop-g5-biodiversity-loss) ’s word, with deep time behind it);
2. *order is nested like the tree* : [fish](https://one-course.com/books/biology/1/en/chapter/14-sorting-living-things#prop-g3-sorting-living-things-groups) appear in deep layers, four-limbed amphibian-kin above them, reptile-kin above those, [mammals](https://one-course.com/books/biology/1/en/chapter/14-sorting-living-things#prop-g3-sorting-living-things-groups) and [birds](https://one-course.com/books/biology/1/en/chapter/14-sorting-living-things#prop-g3-sorting-living-things-groups) higher still — the [classification](https://one-course.com/books/biology/1/en/chapter/21-classifying-animals#def-g4-classifying-animals-classification) ’s boxes ( [Problem 44.1](https://one-course.com/books/biology/1/en/chapter/44-classification-and-kinship#pb-g6-classification-kinship-1) ) stack in time exactly as [kinship](https://one-course.com/books/biology/1/en/chapter/44-classification-and-kinship#prop-g6-classification-kinship-kinship) predicts;
3. *intermediates exist* : the famous slab of *Archaeopteryx* — [feathers](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-covering) and wings on a toothed, long-boned-tailed reptile frame — stands where bird and reptile [branches](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-tree) part; [fossil](#def-g9-evidence-of-evolution-fossils) whales with working hind [legs](https://one-course.com/books/biology/1/en/chapter/4-my-body#def-g1-my-body-parts) stand where [Example 44.5](https://one-course.com/books/biology/1/en/chapter/44-classification-and-kinship#ex-g6-classification-kinship-whale) ’s land-mammal ancestry demanded them.

**Proof.** *Admitted at this level.* ∎

**Example 67.3 (The whale series).**

The whale’s dossier, filled by rocks: successive [fossils](#def-g9-evidence-of-evolution-fossils), in time order, run from a wolf-sized fourlegged shore mammal, through forms with shrinking [legs](https://one-course.com/books/biology/1/en/chapter/4-my-body#def-g1-my-body-parts) and strengthening tails, to legless full swimmers — while today’s whale still builds tiny hidden hip-and-leg [bones](https://one-course.com/books/biology/1/en/chapter/17-bones-and-muscles#def-g3-bones-and-muscles-skeleton) ([Example 44.3](https://one-course.com/books/biology/1/en/chapter/44-classification-and-kinship#ex-g6-classification-kinship-placing) noted the vestiges) and still nurses, breathes air and grows fetal hair. Prediction, [fossils](#def-g9-evidence-of-evolution-fossils), vestiges: three keys, one lock.

![An Archaeopteryx fossil: feathered wings on a toothed, long-tailed reptile frame — an intermediate, standing where the tree’s branches part.](https://one-course.com/images/onecourse/chapters/biology-1/g9-evidence-of-evolution/img-a91090ef03d7.jpg)

*An *Archaeopteryx* [fossil](#def-g9-evidence-of-evolution-fossils): feathered wings on a toothed, long-tailed reptile frame — an intermediate, standing where the tree’s [branches](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-tree) part.*

## 67.2 The witness of living bodies

**Proposition 67.4 (Anatomy remembers).**

Living bodies carry their history:

- *the shared plan* : bat wing, whale flipper, horse [leg](https://one-course.com/books/biology/1/en/chapter/4-my-body#def-g1-my-body-parts) and your [arm](https://one-course.com/books/biology/1/en/chapter/4-my-body#def-g1-my-body-parts) are one [bone](https://one-course.com/books/biology/1/en/chapter/17-bones-and-muscles#def-g3-bones-and-muscles-skeleton) arrangement ( [Problem 44.1](https://one-course.com/books/biology/1/en/chapter/44-classification-and-kinship#pb-g6-classification-kinship-1) ’s [four-limb](https://one-course.com/books/biology/1/en/chapter/4-my-body#def-g1-my-body-parts) fork) stretched, shortened and re-jobbed — inheritance explains what fresh engineering would never repeat;
- *vestiges* : the whale’s hips, the flightless beetle’s sealed wings, your own tailbone and the appendix’s shrunken state — parts kept because ancestry builds on, not from scratch;
- *[embryos](https://one-course.com/books/biology/1/en/chapter/32-human-reproduction#def-g5-human-reproduction-pregnancy) agree* : [vertebrate](https://one-course.com/books/biology/1/en/chapter/21-classifying-animals#def-g4-classifying-animals-vertebrate) [embryos](https://one-course.com/books/biology/1/en/chapter/32-human-reproduction#def-g5-human-reproduction-pregnancy) of [fish](https://one-course.com/books/biology/1/en/chapter/14-sorting-living-things#prop-g3-sorting-living-things-groups) , chick and human run strikingly alike through their early weeks ( [Proposition 58.4](https://one-course.com/books/biology/1/en/chapter/58-from-egg-cell-to-birth#prop-g8-from-egg-to-birth-timetable) ’s plan-laying) — shared build instructions, diverging late.

**Proof.** *Admitted at this level.* ∎

**Proposition 67.5 (The molecules vote).**

The newest witness is [Remark 65.7](https://one-course.com/books/biology/1/en/chapter/65-genes-and-dna#rem-g9-genes-and-dna-universal)’s code. Compare one well-kept [gene](https://one-course.com/books/biology/1/en/chapter/65-genes-and-dna#def-g9-genes-and-dna-gene)’s spelling across [species](https://one-course.com/books/biology/1/en/chapter/30-biodiversity#def-g5-biodiversity-species): human and chimp differ in few letters, human and mouse in more, human and [fish](https://one-course.com/books/biology/1/en/chapter/14-sorting-living-things#prop-g3-sorting-living-things-groups) in more still, human and [yeast](https://one-course.com/books/biology/1/en/chapter/43-producing-our-food#ex-g6-producing-our-food-bread) most — and the distances, tallied [gene](https://one-course.com/books/biology/1/en/chapter/65-genes-and-dna#def-g9-genes-and-dna-gene) after [gene](https://one-course.com/books/biology/1/en/chapter/65-genes-and-dna#def-g9-genes-and-dna-gene), redraw the *same tree* the anatomists drew from [bones](https://one-course.com/books/biology/1/en/chapter/17-bones-and-muscles#def-g3-bones-and-muscles-skeleton) and the paleontologists from layers. Three independent witnesses, one family tree: that agreement is why biologists stopped arguing about *whether* and turned to *how*.

**Proof.** *Admitted at this level.* ∎

**Example 67.6 (Watching it move).**

Change is even watchable where generations turn fast. The peppered moth’s dark form spread through soot-stained industrial woods and receded when the air cleared; insecticide-proof [insects](https://one-course.com/books/biology/1/en/chapter/14-sorting-living-things#prop-g3-sorting-living-things-groups) and antibiotic-defying [microbes](https://one-course.com/books/biology/1/en/chapter/43-producing-our-food#def-g6-producing-our-food-fermentation) ([Chapter 69](https://one-course.com/books/biology/1/en/chapter/69-microbes-and-infection#ch-g9-microbes-and-infection) will meet the medical case) arise within years; island finches’ beak-size distributions shift with drought and plenty, measured live by ring-and-caliper studies. Small moves, short times — the mechanism caught running, whatever its long-run reach.

**Method 67.7 (Weighing historical evidence).**

Evolution is history, and historical claims are tested like the cold case of [Problem 66.1](https://one-course.com/books/biology/1/en/chapter/66-unique-individuals#pb-g9-unique-individuals-1) — by convergence of independent witnesses:

1. ask what the claim *predicts* : which intermediates, which vestiges, which molecular distances;
2. check each witness separately: rocks, bodies, molecules, live watches;
3. weigh their independence: witnesses that could not have colluded, agreeing, multiply credibility;
4. hold the verdict open to the next find — and note when finds keep landing where the claim said to dig (the whale [legs](https://one-course.com/books/biology/1/en/chapter/4-my-body#def-g1-my-body-parts) were sought, and found).

## 67.3 Exercises

**Exercise 67.1 ★.**

What is a [fossil](#def-g9-evidence-of-evolution-fossils), and why do rock layers read as a timeline?

**Solution of Exercise 67.1.**

A preserved trace of past life sealed in sedimentary rock. Layers stack in deposition order, oldest lowest — so upward through the stack is forward through time.

**Exercise 67.2 ★.**

State the layered record’s three testimonies.

**Solution of Exercise 67.2.**

Faunas change layer by layer, most deep [species](https://one-course.com/books/biology/1/en/chapter/30-biodiversity#def-g5-biodiversity-species) [extinct](https://one-course.com/books/biology/1/en/chapter/30-biodiversity#prop-g5-biodiversity-loss); the great groups appear in the tree’s nested order — [fish](https://one-course.com/books/biology/1/en/chapter/14-sorting-living-things#prop-g3-sorting-living-things-groups) deep, four-limbed kin above, [mammals](https://one-course.com/books/biology/1/en/chapter/14-sorting-living-things#prop-g3-sorting-living-things-groups) and [birds](https://one-course.com/books/biology/1/en/chapter/14-sorting-living-things#prop-g3-sorting-living-things-groups) high; and intermediates stand at the [branch](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-tree) points.

**Exercise 67.3 ★.**

What mix of features makes *Archaeopteryx* an intermediate?

**Solution of Exercise 67.3.**

[Feathers](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-covering) and wings — the bird kit — on a frame with teeth and a long bony tail — the reptile kit: both decks in one [animal](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-animal), at the fork the tree draws.

**Exercise 67.4 ★.**

Give three vestiges and what each testifies.

**Solution of Exercise 67.4.**

The whale’s hidden hip-and-leg [bones](https://one-course.com/books/biology/1/en/chapter/17-bones-and-muscles#def-g3-bones-and-muscles-skeleton): a walking ancestry. The flightless beetle’s sealed wings: flying ancestors. The human tailbone (or shrunken appendix): a tailed, differently-fed line. Each is a kept part testifying to a former build.

**Exercise 67.5 ★.**

How do molecular comparisons redraw the tree?

**Solution of Exercise 67.5.**

Count a shared [gene](https://one-course.com/books/biology/1/en/chapter/65-genes-and-dna#def-g9-genes-and-dna-gene)’s letter-differences between [species](https://one-course.com/books/biology/1/en/chapter/30-biodiversity#def-g5-biodiversity-species): the fewer, the closer the kin. The distances, compiled, assemble a tree — and it matches the one [bones](https://one-course.com/books/biology/1/en/chapter/17-bones-and-muscles#def-g3-bones-and-muscles-skeleton) and [fossils](#def-g9-evidence-of-evolution-fossils) drew.

**Exercise 67.6 ★.**

Name two live watches of change from [Example 67.6](#ex-g9-evidence-of-evolution-live).

**Solution of Exercise 67.6.**

The peppered moth’s dark form tracking soot and clean air; insecticide- and antibiotic-proof pests arising in years; the finches’ beak measurements shifting with drought and plenty.

**Exercise 67.7 ★★.**

Why does the shared [limb](https://one-course.com/books/biology/1/en/chapter/4-my-body#def-g1-my-body-parts) plan argue inheritance rather than good design reused? (What would fresh engineering be free to do?)

**Solution of Exercise 67.7.**

Fresh engineering could give each [limb](https://one-course.com/books/biology/1/en/chapter/4-my-body#def-g1-my-body-parts) its best mechanism — struts for wings, hydrofoils for flippers — and would repeat no arbitrary [bone](https://one-course.com/books/biology/1/en/chapter/17-bones-and-muscles#def-g3-bones-and-muscles-skeleton) count. The one arrangement, awkwardly stretched to every trade, is what building-on- inheritance produces and free design would not.

**Exercise 67.8 ★★.**

Assemble the whale’s full dossier: class features, vestiges, [fossil](#def-g9-evidence-of-evolution-fossils) series, molecular kin — one line each.

**Solution of Exercise 67.8.**

Class: [milk](https://one-course.com/books/biology/1/en/chapter/8-how-animals-grow-up#def-g2-animals-grow-up-born), [air-breathing](https://one-course.com/books/biology/1/en/chapter/46-what-is-respiration#def-g7-what-is-respiration-respiration), fetal hair — mammal heirlooms ([Example 44.5](https://one-course.com/books/biology/1/en/chapter/44-classification-and-kinship#ex-g6-classification-kinship-whale)). Vestiges: hidden hips and [leg](https://one-course.com/books/biology/1/en/chapter/4-my-body#def-g1-my-body-parts) [bones](https://one-course.com/books/biology/1/en/chapter/17-bones-and-muscles#def-g3-bones-and-muscles-skeleton). [Fossils](#def-g9-evidence-of-evolution-fossils): the time-ordered series from four-legged shore mammal to legless swimmer. Molecules: its gene-distances place it among the [mammals](https://one-course.com/books/biology/1/en/chapter/14-sorting-living-things#prop-g3-sorting-living-things-groups), hoofed kin nearest. Four witnesses, one dossier.

**Exercise 67.9 ★★.**

Why does the *agreement* of rocks, bodies and molecules count for more than any one witness? Use [Method 67.7](#met-g9-evidence-of-evolution-weigh)’s independence step.

**Solution of Exercise 67.9.**

Because the witnesses could not collude: rocks were laid, bodies built and molecules spelled by processes with no access to each other’s testimony. Independent witnesses agreeing multiply credibility — one tree from three sources is the convergence the method prizes.

**Exercise 67.10 ★★.**

“No rabbits among the trilobites.” Why is that absence — sustained across every dig ever made — itself strong evidence?

**Solution of Exercise 67.10.**

Because the claim forbids it: [mammals](https://one-course.com/books/biology/1/en/chapter/14-sorting-living-things#prop-g3-sorting-living-things-groups) must not appear below the layers of their ancestors. Every dig is a fresh chance to falsify — and the absence, sustained across every excavation ever made, is the claim passing its test daily.

**Exercise 67.11 ★★.**

The [embryo](https://one-course.com/books/biology/1/en/chapter/32-human-reproduction#def-g5-human-reproduction-pregnancy) witness: what agrees, when does it diverge, and which chapter’s machinery says why shared early instructions matter most?

**Solution of Exercise 67.11.**

[Vertebrate](https://one-course.com/books/biology/1/en/chapter/21-classifying-animals#def-g4-classifying-animals-vertebrate) [embryos](https://one-course.com/books/biology/1/en/chapter/32-human-reproduction#def-g5-human-reproduction-pregnancy) agree strikingly through the early plan-laying weeks and diverge late. The development chapter’s machinery says why: early instructions lay the shared body plan — the deepest, oldest chapters of the text — while later reading writes the [species](https://one-course.com/books/biology/1/en/chapter/30-biodiversity#def-g5-biodiversity-species)’ particulars. Shared early text, shared deep ancestry.

**Exercise 67.12 ★★★.**

Write the chapter’s argument as [Method 67.7](#met-g9-evidence-of-evolution-weigh) applied in full: claim, predictions, four witnesses, verdict — and the question the verdict hands to [Chapter 68](https://one-course.com/books/biology/1/en/chapter/68-how-species-change#ch-g9-how-species-change).

**Solution of Exercise 67.12.**

Claim: [species](https://one-course.com/books/biology/1/en/chapter/30-biodiversity#def-g5-biodiversity-species) change and share descent. Predictions: time-ordered faunas in the tree’s nesting; intermediates at forks; vestiges of former builds; molecular distances grading with [kinship](https://one-course.com/books/biology/1/en/chapter/44-classification-and-kinship#prop-g6-classification-kinship-kinship). Witnesses: the rocks deliver the order and the intermediates; bodies deliver plan and vestiges; molecules deliver the matching tree; live watches deliver change in motion. Verdict: descent with change stands on convergent independent testimony — and hands the next chapter its question: *what drives the change?*

## 67.4 Problem: The Museum’s New Wing

**Problem 67.1.**

Weekend problem — curating the evidence hall

The natural history museum builds an evolution wing, and the class curates four rooms: Rocks, Bodies, Molecules, Live Watches.

**Part I — Room by room.**

1. Rocks: order the wall — trilobite slab, first [fish](https://one-course.com/books/biology/1/en/chapter/14-sorting-living-things#prop-g3-sorting-living-things-groups) , amphibian-kin tracks, reptile [skeletons](https://one-course.com/books/biology/1/en/chapter/17-bones-and-muscles#def-g3-bones-and-muscles-skeleton) , *Archaeopteryx* cast, early mammal jaw — and write the room’s one-sentence caption from [Proposition 67.2](#prop-g9-evidence-of-evolution-record) .
2. Bodies: the centerpiece spreads bat wing, whale flipper, horse [leg](https://one-course.com/books/biology/1/en/chapter/4-my-body#def-g1-my-body-parts) and human [arm](https://one-course.com/books/biology/1/en/chapter/4-my-body#def-g1-my-body-parts) from one [skeleton](https://one-course.com/books/biology/1/en/chapter/17-bones-and-muscles#def-g3-bones-and-muscles-skeleton) stand. Caption the shared plan — and add the vestige cabinet’s three exhibits.
3. Molecules: the wall chart tallies one [gene](https://one-course.com/books/biology/1/en/chapter/65-genes-and-dna#def-g9-genes-and-dna-gene) ’s letter-differences: chimp 1, mouse 8, [fish](https://one-course.com/books/biology/1/en/chapter/14-sorting-living-things#prop-g3-sorting-living-things-groups) 24, [yeast](https://one-course.com/books/biology/1/en/chapter/43-producing-our-food#ex-g6-producing-our-food-bread) 41 (illustrative counts). What must the chart’s tree match, for the room to work?
4. Live Watches: choose two exhibits from [Example 67.6](#ex-g9-evidence-of-evolution-live) and say what each shows moving.

**Part II — The visitors’ questions.**

5. “Why are there still monkeys, if we descend from ancestors shared with them?” Answer with the tree’s branching — cousins, not ladders ( [Definition 44.6](https://one-course.com/books/biology/1/en/chapter/44-classification-and-kinship#def-g6-classification-kinship-tree) ).
6. “Where are the missing links?” Point to the found ones — two from this chapter — and state what each stood between.
7. “Is evolution not just a theory?” Answer with the historical-evidence method: what “theory” means here, and what the four rooms’ agreement establishes.
8. “Could tomorrow’s dig overturn it?” State what kind of find would — rabbits among trilobites — and what its absence, dig after dig, has meant.

**Part III — The wing’s closing panel.**

9. Draft the panel linking the wing to the [classification](https://one-course.com/books/biology/1/en/chapter/21-classifying-animals#def-g4-classifying-animals-classification) hall next door: why the old nested boxes were the tree all along.
10. Add the molecule paragraph: what the shared code says about the trunk.
11. Add the honest paragraph: what the wing shows (change, [kinship](https://one-course.com/books/biology/1/en/chapter/44-classification-and-kinship#prop-g6-classification-kinship-kinship) , intermediates) and what it does not yet explain — naming the mechanism question the next hall will take up.
12. Close with one sentence a twelve-year-old will remember, containing *family* and *time* .

**Solution of Problem 67.1.**

**1.** Order: trilobites lowest, then first [fish](https://one-course.com/books/biology/1/en/chapter/14-sorting-living-things#prop-g3-sorting-living-things-groups), amphibian-kin tracks, [reptiles](https://one-course.com/books/biology/1/en/chapter/21-classifying-animals#prop-g4-classifying-animals-classes), *Archaeopteryx*, early mammal jaw. Caption: “Read upward, the rocks change cast in exactly the order the family tree predicts — with the in-betweens standing at the branchings.”

**2.** Caption: “One [bone](https://one-course.com/books/biology/1/en/chapter/17-bones-and-muscles#def-g3-bones-and-muscles-skeleton) plan — stretched to fly, paddle, gallop and write: inheritance re-jobbed, never redesigned.” Cabinet: the whale’s hips, the sealed beetle wings, the human tailbone.

**3.** The tree implied by the letter-counts — chimp nearest, [yeast](https://one-course.com/books/biology/1/en/chapter/43-producing-our-food#ex-g6-producing-our-food-bread) farthest — must match the anatomists’ and paleontologists’ tree next door: same branching, independently derived.

**4.** The moths: a [population](https://one-course.com/books/biology/1/en/chapter/55-reproduction-and-the-environment#def-g8-reproduction-and-environment-population)’s colors tracking its [environment](https://one-course.com/books/biology/1/en/chapter/37-exploring-our-environment#def-g6-exploring-our-environment-components) within decades. The finches: beak distributions moving with the [seed](https://one-course.com/books/biology/1/en/chapter/9-from-seed-to-plant#def-g2-from-seed-to-plant-seed) supply, caliper-measured — inheritance-fed change, watched live.

**5.** Because descent [branches](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-tree): we and today’s monkeys are cousins on separate [branches](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-tree) of a shared fork — no one alive is anyone’s ancestor, and a cousin’s existence no more denies [kinship](https://one-course.com/books/biology/1/en/chapter/44-classification-and-kinship#prop-g6-classification-kinship-kinship) than your cousins deny yours.

**6.** *Archaeopteryx*, standing between reptile frame and bird kit; the legged [fossil](#def-g9-evidence-of-evolution-fossils) whales, standing between shore mammal and swimmer. Both were predictions before they were finds.

**7.** In science “theory” names an explanation tested until it organizes a field — not a guess. What the rooms establish is the historical fact of change and descent, by convergent independent witnesses; the theory proper is the mechanism the next hall explains.

**8.** A true anachronism — mammal [bones](https://one-course.com/books/biology/1/en/chapter/17-bones-and-muscles#def-g3-bones-and-muscles-skeleton) below trilobite layers, verified — would break the order the claim demands. That no dig in two centuries has produced one is the claim surviving its hardest test, every day, everywhere digging continues.

**9.** “The boxes-in-boxes you met next door were never filing convenience: [attributes](https://one-course.com/books/biology/1/en/chapter/44-classification-and-kinship#def-g6-classification-kinship-attribute) nest because descent [branches](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-tree) — the [classification](https://one-course.com/books/biology/1/en/chapter/21-classifying-animals#def-g4-classifying-animals-classification) was the family tree, drawn before anyone knew what it drew.”

**10.** “Every exhibit in this wing, and every visitor before it, writes its build in the same four letters read by the same code: the [branches](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-tree) differ, the trunk’s language never has.”

**11.** “This wing shows that [species](https://one-course.com/books/biology/1/en/chapter/30-biodiversity#def-g5-biodiversity-species) change, that they share descent, and that the record keeps the in-betweens. What it has not yet said is what *drives* the change — the mechanism hall is next, and its answer runs on variety, inheritance and the [environment](https://one-course.com/books/biology/1/en/chapter/37-exploring-our-environment#def-g6-exploring-our-environment-components)’s checks.”

**12.** “All life is one family album, and the rocks kept the early pages — given time, cousins grow as different as whales and bats, and stay family.”