Vice-captain Daniel Carter sits on 85 appearances, with Saturday's test his 71st at No 10, a record for an All Black first five-eighths.
More solidity comes further out with centre Conrad Smith ready to guide the new back three, in his 56th test.
He and fullback Israel Dagg are the only backline survivors from the World Cup final while Read, McCaw, Sam Whitelock, Owen Franks and Tony Woodcock remain in the pack.
Retallick will be just two days older than Mark Cooksley who was the youngest lock to debut for the All Blacks at 21 years and sevens days.
Left wing Savea is also 21, while new halfback Smith is 23 and in just his second full season of Super rugby.
Those who have missed the squad for the first of three tests against Ireland are Hosea Gear, Tamati Ellison, Ma'a Nonu, Beauden Barrett, Sam Cane, Luke Romano, Ben Tameifuna and Wyatt Crockett.
Nonu's enforced rest means Sonny Bill Williams will start his 15th test sandwiched between the senior backline men, Carter and Smith.
Retallick has beaten veteran Ali Williams for the role as right-side lock in the scrum after a superb debut season with the Chiefs.
The young lock's allround game, sting in the setpiece and around the field, has been a boon for selectors Steve Hansen, Ian Foster and Grant Fox, who have been searching for a solution to the departure of Brad Thorn.
So far, Retallick suggests he could have a lengthy international career if his massive frame hangs together.
The other move in the pack is to use Victor Vito on the blindside instead of the rangy Adam Thomson.
Ireland will bring a strong forward threat in phase play and Vito's renewed emphasis on defence and his power game have been picked as part of the All Black antidote.
Smith's rise to starting halfback has been quickfire. He has surged past the three World Cup halfbacks - Piri Weepu, Andy Ellis and Jimmy Cowan - impressing the panel that his swift pass and nimble game will stand up to the rigours of test rugby.
It is a remarkable rise and a bold decision by the selectors, one that will receive as much inspection as their use of Weepu when he is called from the bench.
Savea earned his place in the original squad with some thundering work down the left flank for the Hurricanes and a renewed certainty under the high ball. When Cory Jane and Richard Kahui fell to injury, Savea's test debut became automatic, with Zac Guildford earning the switch to the right flank.
Starting XV (tests):
1. Tony Woodcock (83)
2. Andrew Hore (62)
3. Owen Franks (31)
4. Brodie Retallick *
5. Samuel Whitelock (25)
6. Victor Vito (13)
7. Richie McCaw - captain (103)
8. Kieran Read (36)
9. Aaron Smith *
10. Daniel Carter (85)
11. Julian Savea *
12. Sonny Bill Williams (14)
13. Conrad Smith (55)
14. Zac Guildford (8)
15. Israel Dagg (12)
* Debut
Reserves:
16. Hikawera Elliot (2)
17. Ben Franks (15)
18. Ali Williams (73)
19. Adam Thomson (24)
20. Piri Weepu (56)
21. Aaron Cruden (9)
22. Ben Smith (2)
