Some dictionary definitions ...

(from Dictionary.com Unabridged (v 1.1)
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2006.)

collaborate [kuh-lab-uh-reyt]

–verb (used without object), -rated, -rating.

1. to work, one with another; cooperate, as on a literary work: They collaborated on a novel.

2. to cooperate, usually willingly, with an enemy nation, esp. with an enemy occupying one's country: He collaborated with the Nazis during World War II.

[Origin: 1870–75; LL collabōrātus (ptp. of collabōrāre), equiv. to col- col-1 + labor work + -ātus -ate1]

—Related forms
collaborator, noun

—Synonyms. collude, join, assist, abet.

collaboration [kuh-lab-uh-rey-shuhn]
–noun

1. the act or process of collaborating.

2. a product resulting from collaboration: This dictionary is a collaboration of many minds.

We discussed as a group the difference between collaboration, altruism and symbiosis ...

altruism [al-troo-iz-uhm]
–noun

1. the principle or practice of unselfish concern for or devotion to the welfare of others (opposed to egoism).

2. Animal Behavior. behavior by an animal that may be to its disadvantage but that benefits others of its kind, as a warning cry that reveals the location of the caller to a predator.

[Origin: 1850–55; F altruisme, equiv. to autru(i) others (VL *alterui, obl. form of L alter other (F autre), with -ui from cui to whom; -l- restored from L alter) + -isme -ism; popularized through trans. of A. Comte, who perh. coined it, on the model of égoisme egoism]

symbiosis [sim-bee-oh-sis, -bahy-]
–noun, plural -ses [-seez]

1. Biology.
a.the living together of two dissimilar organisms, as in mutualism, commensalism, amensalism, or parasitism.
b.(formerly) mutualism (def. 1).

2. Psychiatry. a relationship between two people in which each person is dependent upon and receives reinforcement, whether beneficial or detrimental, from the other.

3. Psychoanalysis. the relationship between an infant and its mother in which the infant is dependent on the mother both physically and emotionally.

4. any interdependent or mutually beneficial relationship between two persons, groups, etc.

[Origin: 1615–25; Gk symbíōsis, equiv. to sym- sym- + biō (var. s. of bioûn to live) + -sis -sis]

—Related forms
symbiotic [sim-bee-ot-ik, -bahy-], symbiotical, adjective
symbiotically, adverb

We felt that collaboration was closer to symbiosis than altruism.
What about synergy?

synergy [sin-er-jee]
–noun, plural -gies.

1. combined action or functioning; synergism.

2. the cooperative action of two or more muscles, nerves, or the like.

3. the cooperative action of two or more stimuli or drugs.

[Origin: 1650–60; NL synergia Gk synergía, equiv. to synerg(ós)]

—Related forms
synergic [si-nur-jik], adjective

So symbiosis and synergy are both close in meaning to collaboration. They are also both terms most commonly used in biology, which made me wonder whether collaboration need necessarily always be a conscious, intentional thing. A bee and a flower could be said to work collaboratively. A college, a city, a language, an economy could all be thought of in terms of large-scale collaborative efforts, which made me begin to think in terms of Deleuzian Rhizomes ...

The question I am left with is, what is not a collaboration?