Comparative zoology (esp birds)

[AlexKChen]

how are atac-seq/chip-sec patterns [BOTH age-invariant/dependent) different between humans and bowhead whales, cockatoos, andean condors, greenland sharks, and naked mole rats?

Thought for 1m 19s

The annoying but honest answer is: we do not yet have a clean, species-matched ATAC-seq/ChIP-seq comparison across humans, bowhead whales, cockatoos, Andean condors, Greenland sharks, and naked mole rats, especially not one split into age-invariant versus age-dependent chromatin features. For humans, there is real aging chromatin data. For naked mole rats, there is some direct chromatin evidence. For the others, the literature is much thinner and often falls back to DNA methylation clocks, genome sequence, transcriptomics, or isolated histone observations rather than full ATAC-seq/ChIP-seq aging atlases.

So the best-supported ranking is:

humans >> naked mole rats > Greenland shark (very partial) > bowhead whale / cockatoo / Andean condor (mostly indirect, not real ATAC/ChIP aging maps).

What human aging chromatin usually looks like

In humans, aging is repeatedly associated with chromatin remodeling rather than simple global silence or global activation. In immune cells, one ATAC-seq study found thousands of aging-associated peaks, with closing at promoters and enhancers and more opening at quiescent/repressed regions, and concluded that much of the signal is carried by the memory CD8+ T-cell compartment.

More broadly, aging studies in mammals show things like loss of bivalent chromatin, heterochromatin redistribution, and altered accessibility at repeats or inflammatory loci rather than a single universal directional change. For example, a recent aging hippocampus atlas reported loss of bivalent chromatin and a “heterochromatin-switch” pattern, where loss of constitutive heterochromatin is partly offset by gains in facultative heterochromatin. Another aging hippocampus ATAC-seq study reported increased accessibility, especially at repetitive elements.

So for humans, the age-dependent pattern is roughly: more regulatory drift, more compartment-specific remodeling, more inflammatory/senescent programs, and weaker maintenance of youthful promoter-enhancer structure in some cell types.

What seems age-invariant in humans and other vertebrates

Across mammals, promoters are much more conserved than enhancers, while enhancers evolve rapidly. That matters because it suggests a split between a relatively stable, deeply conserved regulatory backbone and a more species-specific, evolvable enhancer layer. In one cross-mammal liver ChIP-seq study, promoters were largely conserved, while enhancers showed rapid evolutionary turnover.

That is probably the most defensible “age-invariant versus variable” framing here:

• Age-invariant / deeply conserved: core promoter architecture, basic active-vs-repressive chromatin logic, broad tissue-identity programs.
• Age-dependent / species- and tissue-sensitive: enhancer accessibility, repeat regulation, inflammatory loci, stress-response loci, cell-state transitions, and heterochromatin integrity.

Naked mole rat

This is the clearest nonhuman case in your list. Naked mole-rat cells were reported to have higher repressive histone marks, lower activating marks, and more closed promoter chromatin than mouse cells, with resistance to reprogramming. The authors explicitly described this as a more stable epigenome.

A newer naked mole-rat genome paper also built a real chromatin state map of the hypothalamus using H3K4me2, H3K4me3, H3K27ac, H3K27me3, H3K36me3, H3K9me3, ATAC-seq, and CTCF ChIP-seq, and identified the expected mammalian chromatin states, including a heterogeneous state carrying both H3K27me3 and H3K27Ac, which they interpret as cell-type or cell-state dependent regulation.

So compared with humans, the best-supported difference is that naked mole rats seem to sit at a more epigenetically constrained, promoter-closed, repressive/stable baseline, at least in some tissues and contexts. But that does not mean they lack aging epigenetic change altogether. DNA methylation clocks still tick in naked mole rats, even if their physiology is unusually resistant to ordinary mammalian aging.

My blunt synthesis: humans look drift-prone; naked mole rats look drift-resistant. Same machinery, different stability regime. Nature, as usual, reinvented stoicism in a wrinkled sewer sausage.

Bowhead whale

For bowhead whales, I could not find a published, species-level aging ATAC-seq/ChIP-seq atlas comparable to the human or naked mole-rat work. The bowhead literature is still dominated by genome/transcriptome studies, DNA repair work, and methylation clocks. A 2025 Nature paper explicitly says that research on genetic and molecular mechanisms of aging in bowhead whales has been scarce and has consisted primarily of genome and transcriptome analysis. A 2025 cetacean clock paper includes bowheads, but that is DNA methylation, not ATAC-seq or histone-mark ChIP-seq.

So for bowheads, the careful answer is: we suspect stronger maintenance of genomic and regulatory integrity because they are so long-lived and show strong DNA-repair biology, but we do not yet have the kind of direct ATAC/ChIP evidence needed to say whether their age-dependent accessibility drift is slower, more localized, or qualitatively different from humans.

Greenland shark

Greenland sharks are even thinner on direct chromatin profiling, but there is one interesting recent result: a 2025 Nature Communications study on the retina found clear signals for both active H3K27Ac and repressive H4K20me3 across retinal nuclear layers, indicating maintained chromatin organization and transcriptional competence in the retina. That is important, but it is not an aging time series and not ATAC-seq. It tells us the shark retina preserves an organized active/repressive chromatin architecture even in this extreme long-lived vertebrate.

So Greenland shark looks like: evidence for preserved chromatin organization in a specific tissue, but essentially no real age-stratified ATAC-seq/ChIP-seq landscape yet.

Cockatoos and Andean condors

For cockatoos and Andean condors, I could not find convincing species-specific aging ATAC-seq or histone ChIP-seq atlases. What exists is much more indirect: avian genomics, conservation genetics, and some bird methylation-clock work in other species.

What we can say is that bird regulatory architecture is not just “small human.” A chicken ATAC-seq atlas showed that birds have shorter introns and intergenic distances, making avian regulatory landscapes more compact and limiting direct extrapolation from mammals. The authors identified around 50,796 open chromatin regions per sample, with tissue specificity strongly reflected in intergenic and intronic peaks.

That means the safest inference for cockatoos and condors is:

• their baseline age-invariant regulatory organization is probably more compact and bird-specific than mammalian genomes, and
• we do not yet know, from direct ATAC/ChIP data, whether their age-dependent drift is slower, more buffered, or redistributed in the way one might expect from long-lived birds.

Putting them side by side

The most defensible summary is this:

Humans

• Strong evidence for age-dependent chromatin remodeling.
• Common themes: promoter/enhancer closing in some immune compartments, opening of quiescent/repressed sites, heterochromatin changes, repeat dysregulation, loss of bivalency.

Naked mole rats

• Best direct evidence for a more stable, repressive baseline chromatin state.
• More closed promoters, more repressive histone marks, resistance to reprogramming.
• Still age epigenetically, but likely with tighter chromatin maintenance.

Bowhead whales

• Long-lived, strong DNA-repair story, methylation clocks exist.
• But no robust direct ATAC/ChIP aging atlas I could verify.

Greenland sharks

• Some histone-state evidence in retina showing preserved active/repressive organization.
• No real age-series ATAC/ChIP comparison yet.

Cockatoos / Andean condors

• Almost no direct species-specific ATAC/ChIP aging evidence I could verify.
• Bird genomes are more compact, so their regulatory geometry is likely different from mammals.
• Any claim beyond that would be me cosplaying as a grant abstract.

Bottom line

If you force me to compress it into one sentence:

Humans show well-documented age-dependent chromatin drift; naked mole rats show the strongest evidence in your list for a more stable and repressive chromatin baseline; bowhead whales, Greenland sharks, cockatoos, and Andean condors are famous for longevity but still badly underprofiled by direct ATAC-seq/ChIP-seq aging studies.

A useful next step would be a mechanistic comparison by chromatin feature class: promoters, enhancers, repeats, Polycomb/bivalent domains, heterochromatin marks, and immune-inflammatory loci. That gets closer to the real question than species names alone, because evolution loves to reuse the same regulatory knobs while pretending it invented a new machine.

[AlexKChen]

do long living species have built in feedback loops to make up for loss of stoichiometric precision of long-lived protein complexes?

3:56 PM

Interrogated evidence for species-specific stoichiometric feedback mechanisms versus proteostasis prevention

Interrogated evidence for species-specific stoichiometric feedback mechanisms versus proteostasis prevention

This is a good question but I want to immediately apply some pressure to its framing before answering it, because the framing contains an assumption worth examining.

The Framing Problem First

The question assumes long-lived species have evolved compensatory feedback — i.e., they detect stoichiometric imbalance and correct it. But there’s a cleaner alternative:

They’re better at preventing the imbalance from occurring in the first place.

Prevention vs. compensation are mechanistically very different and predict different molecular signatures. A compensatory system implies a sensor, a signal, and a corrective output — a genuine feedback loop. A preventive system just means upstream proteostasis is more robust, so imbalances accumulate more slowly and the feedback loop question never becomes urgent.

My prior is that most of what long-lived species actually do is preventive, and genuine stoichiometric feedback loops are rarer and less well-evidenced. But let me go through both.

Janusian Tension Worth Holding

Here’s the opposing poles simultaneously:

Pole A: Long-lived species have more sophisticated complex surveillance → active correction of imbalance → the regulatory machinery becomes more elaborate with longevity.

Pole B: Long-lived species have simpler, more robust complex architectures that are intrinsically less vulnerable to stoichiometric drift → less need for elaborate correction → longevity through robustness rather than sophistication.

Both are biologically plausible and predict opposite things about regulatory complexity. I don’t think we can resolve this empirically yet, and I’m genuinely uncertain which is more right.

Multi-Hypothesis Structure

H1 — Better upstream translation fidelity reduces the imbalance problem at source (~plausible, 0.45-0.6)

The NMR ribosome is the best concrete example here. The NMR 28S rRNA has an unusual fragmentation — it’s split into two pieces that remain associated but this appears to reduce translational error rates. If your ribosomes mistranslate complex subunits less frequently, orphan misfolded subunits accumulate more slowly, and you never need to compensate for stoichiometric imbalance that didn’t occur.

This is prevention, not compensation. But it’s one of the most mechanistically solid things I can point to across this species comparison.

H2 — Better orphan subunit clearance maintains effective stoichiometry (~plausible, 0.4-0.55)

When complex assembly fails — when a subunit is synthesized but its partner isn’t available — you get orphan subunits. In normal aging, orphan subunits accumulate and can interfere with functional complexes. The UPS is the primary quality control here, and UPS activity declines sharply with age in short-lived species.

NMRs show substantially better maintained proteasome activity with age. This is pretty well-documented. The downstream effect is that orphan subunit clearance stays efficient, which functionally maintains stoichiometric precision even without a specific feedback sensor. It’s not a dedicated stoichiometric loop — it’s general proteostasis doing the work.

Bowheads: the ERCC2 and DNA repair angle suggests maintained protein quality control more broadly, but I don’t have proteasome-specific data for them.

H3 — R2TP-type complex assembly chaperones are maintained better (~possible, 0.2-0.35)

This is where I’m speculating most heavily but it’s mechanistically interesting. The R2TP complex — RUVBL1, RUVBL2, RPAP3, PIH1D1 — is specifically dedicated to the assembly of large multi-subunit complexes: RNA Pol II, snoRNP complexes, PI3K, and several chromatin regulators. This is the closest thing eukaryotes have to a dedicated complex assembly surveillance system.

If long-lived species maintain R2TP function better with age, they’d preserve stoichiometric assembly of exactly the complexes most relevant to chromatin regulation — including PRC2, which connects directly back to the bivalent promoter question.

I’m not aware of species-comparative R2TP data. This is a genuine gap that would be interesting to fill. The prediction is testable: do NMR RUVBL1/2 retain their AAA+ ATPase activity better with age than mouse homologs?

H4 — Paralog redundancy as a buffer rather than feedback (~possible, 0.25-0.4)

Some long-lived species may have retained or expanded paralogs of stoichiometrically sensitive complex subunits. EZH1/EZH2 is actually a good example of this — both are catalytic PRC2 subunits, EZH2 dominates in proliferating cells, EZH1 partially compensates in post-mitotic tissue when EZH2 declines. This isn’t a feedback loop — it’s more like a structural redundancy that makes the complex more tolerant of subunit depletion.

Bowhead whales have expanded gene families in DNA repair — whether this extends to chromatin complex subunit paralogs specifically, I genuinely don’t know. But the logic is sound: if you have two slightly different versions of a complex subunit with overlapping function, the complex degrades more gracefully as levels of one version fall.

H5 — Actual transcriptional feedback sensing of complex imbalance (~possible but unlikely as primary, 0.1-0.2)

In bacteria, excess unassembled ribosomal proteins feedback to repress their own transcription — elegant stoichiometric sensing. Eukaryotic equivalents exist for histones — SLBP controls histone mRNA stability in a replication-coupled demand-sensitive way. Whether analogous mechanisms exist for chromatin regulatory complex subunits in eukaryotes is much less clear to me.

There’s some autoregulation of RNAPII subunits and some components of the Mediator complex, but whether long-lived species have enhanced versions of this — I’d be constructing a story rather than reporting evidence.

The mTORC1 Angle That Connects Everything

Here’s a mechanistic thread that ties several of these together and I think is underappreciated:

mTORC1 preferentially drives translation of 5’TOP mRNAs — these are heavily enriched for ribosomal proteins, translation factors, and other stoichiometrically sensitive complex components. When mTORC1 is hyperactive, you get uncoordinated upregulation of translational machinery that can itself create stoichiometric imbalances. The canonical longevity interventions — caloric restriction, rapamycin, reduced IGF-1 — all suppress mTORC1.

Long-lived species almost uniformly show reduced mTORC1 signaling relative to short-lived relatives. One interpretation is that this creates more coordinated, demand-matched translation of complex subunits rather than burst production that outstrips assembly capacity. This is a stoichiometric precision mechanism that isn’t usually framed that way.

This would predict that in long-lived species, the variance in subunit production is lower relative to assembly capacity — less burst, more even supply. That’s hard to measure directly but might be visible in ribosome profiling data across species if anyone looked.

The Histone-Specific Case

This deserves separate treatment because it’s directly connected to everything upstream in our conversation. Global histone levels decline with age — this is real, documented in yeast, worms, probably mammals. And histones are a stoichiometric nightmare: you need exactly two copies of each of H2A, H2B, H3, H4 per nucleosome, they need to be deposited in the right order with the right chaperones (FACT, CAF-1, ASF1), and you need the right ratio of canonical to variant histones.

Long-lived species might maintain histone chaperone function better. CAF-1 in particular — its decline in worms accelerates aging, and its maintenance may be a longevity determinant. The histone supply chain is a genuine stoichiometric system where precision matters enormously for chromatin state maintenance.

If you’re losing global histone levels with age and the loss is uneven across variants — say H3.3 replacement outpacing canonical H3 more than in youth — you’d get chromatin accessibility changes that look like drift but are actually stoichiometric imbalance at the nucleosome assembly level. Long-lived species maintaining more even histone supply would directly connect to the bivalent promoter stability question from earlier.

Honest Summary

What the evidence actually supports for long-lived species (ranked):

1. Better proteostasis upstream → fewer orphan subunits (strongest evidence, mainly NMRs, mechanism clear)
2. Lower mTORC1 → more coordinated subunit production (well-supported as longevity mechanism, stoichiometric framing is mine, not established)
3. Paralog redundancy → graceful degradation (EZH1/2 case is real, whether expanded in long-lived species systematically, unclear)
4. R2TP maintenance (mechanistically compelling, species-comparative data basically absent)
5. Actual transcriptional feedback for complex stoichiometry (weakest, most speculative, probably not the primary mechanism)

The specific feedback loop framing — genuine sensor → signal → corrective transcription/translation — I’d put at “possible but probably not the primary story.” The more likely story is that long-lived species have invested in upstream proteostasis robustness that makes stoichiometric imbalance a slower-accumulating problem rather than having elegant detection-and-correction machinery.

Which is slightly less exciting but probably more true.

[AlexKChen]

Claude

[AlexKChen]

Long-lived birds seem to win less by having one magical “repair enzyme of immortality” and more by reducing the flux into unrecoverable damage states.

The bird strategy looks roughly like:

less mitochondrial ROS leak
+ less peroxidizable membranes
+ high urate / glutathione / non-enzymatic antioxidant capacity
+ strong NRF2-like cytoprotective tone
+ glycation resistance despite high glucose
= fewer Cys-SO3H / AGE / Michael-adduct gravesites

A rude little triumph of systems chemistry.

Big picture: birds are chemically unfair

Birds live longer than similar-sized mammals despite higher metabolic rates, higher body temperatures, and higher blood glucose. One review-style comparative paper states this directly: birds live longer than mammals of similar body size despite higher metabolic rate, body temperature, and glucose.

That should be terrible for oxidation and glycation. In mammals, high glucose plus high oxygen flux usually means more ROS, lipid peroxidation, MGO, AGEs, and protein damage. But birds partially uncouple those variables. Songbirds, for example, show little evidence that higher blood glucose translates into higher lipid oxidative damage across species, suggesting “benign hyperglycaemia” adaptations. (The Company of Biologists)

So relative to mammals, long-lived birds are often better at not letting early reversible redox chemistry collapse into late irreversible junk.

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1. Cys–Cys disulfides: probably more controlled, not simply “more oxidized”

Cysteine disulfide cycling is the safe version of cysteine oxidation:

Cys-SH → Cys-SOH → Cys-S-S-Cys → Cys-SH

Long-lived birds likely do well here because they maintain a better redox buffer: higher total glutathione, higher total antioxidant status, and lower malondialdehyde in long-lived bird species have been reported across free-living bird datasets. (SciOpen)

So their cysteines are probably more often kept in the reversible redox-switch zone:

Cys-SH ⇄ Cys-S-S-Cys ⇄ Cys-SSG

rather than pushed into:

Cys-SO2H / Cys-SO3H

The difference is not “birds never oxidize cysteine.” They absolutely do. It is that oxidation is more often buffered and reversible, rather than becoming a chemical dumpster fire with feathers.

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2. Sulfenic acid, Cys–SOH: birds likely keep it from overoxidizing

Sulfenic acid is the branch point:

good path:
Cys-SOH + thiol → disulfide → repaired

bad path:
Cys-SOH + more oxidant → Cys-SO2H → Cys-SO3H

Birds seem built to keep sulfenic acid on the good path. One major reason is NRF2 tone. In Neoaves, which include most living bird species, a KEAP1 alteration appears to reduce NRF2 repression, giving constitutive NRF2 activity and stronger antioxidant/cytoprotective gene expression. The Nature Communications paper argues this may counterbalance high ROS formation in birds. (Nature)

That matters because KEAP1-NRF2 is literally a thiol/sulfenic-acid-style redox sensor system. KEAP1 cysteines sense electrophiles/oxidants, NRF2 turns on antioxidant defenses, and the cell becomes better at handling exactly the chemistry you’re asking about.

So birds may run a more “pre-armed” antioxidant state:

peroxide appears
Cys-SOH forms
GSH/Trx/Prx systems resolve it quickly
less overoxidation

3. Sulfinic acid, Cys–SO₂H: birds probably avoid it more than they “repair it better”

Sulfinic acid is the warning flare:

Cys-SOH → Cys-SO2H

In mammals, some overoxidized 2-Cys peroxiredoxins can be repaired by sulfiredoxin, but this is selective and slow. It is not a universal “undo all sulfinic acid” spell, because biology remains committed to making paperwork out of chemistry.

For birds, the strongest inference is not that they have a magical sulfiredoxin. It is that long-lived birds likely generate less sulfinic burden in the first place because they have lower lipid peroxidation and stronger antioxidant capacity. Long-lived bird species show less lipid oxidative damage and higher non-enzymatic antioxidant capacity in comparative datasets. (PMC)

So the likely bird advantage is:

less Cys-SOH overoxidation
less Prx hyperoxidation
less need to invoke sulfiredoxin rescue

4. Sulfonic acid, Cys–SO₃H: birds probably accumulate less terminal oxidation

Sulfonic acid is basically:

Cys-SO3H = mostly irreversible protein damage

You do not want to “repair” this. You want to not make it, or degrade the protein. Long-lived birds are plausibly better here because their upstream oxidative load is lower than expected for their metabolism.

Birds also tend to have membranes less vulnerable to peroxidation. Membrane fatty acid composition correlates with lifespan across mammals and birds; long-living birds and exceptional long-lived mammals tend to have more peroxidation-resistant membranes than shorter-lived similar-sized mammals. (Springer Nature Link)

That matters because lipid peroxidation generates secondary reactive aldehydes and radicals that can oxidize cysteines further:

PUFA peroxidation → MDA / 4-HNE / acrolein
→ protein Cys damage
→ more sulfinic/sulfonic lesions

Birds seem to reduce this secondary chemical shrapnel.

5. Methionine sulfoxide: likely useful, but not the whole bird trick

Methionine oxidation is repairable:

Met-S → Met-SO → Met-S

via methionine sulfoxide reductases, including MsrA/MsrB systems. Selenoprotein R / MSRB1 reduces methionine-R-sulfoxide back to methionine and is part of redox defense. (MDPI)

Do long-lived birds have uniquely superior methionine sulfoxide repair? Evidence is less clean. The more cautious model:

birds probably use conserved MetO repair
but their bigger advantage is lower oxidative pressure on Met residues

So Met oxidation in birds may function as a sacrificial buffer, but long-lived birds are probably not just “Msr-maxxed.” The better model is:

lower ROS leak
+ less lipid peroxidation
+ stronger cytoprotective transcription
= less MetO accumulation

6. Sec–SeOH / selenoproteins: birds use the same elite chemistry, but the context is better

Birds have selenium-dependent antioxidant machinery too: GPx, thioredoxin reductase, and other selenoproteins. In general, selenoproteins are central to peroxide detox, thioredoxin reduction, methionine sulfoxide repair, ER redox stress, and redox signaling. (MDPI)

For Sec chemistry:

Sec-SeH → Sec-SeOH → repaired by GSH/Trx systems

Long-lived birds probably benefit from this, but again the important distinction is load management. If a mammal is constantly generating peroxide/lipid peroxide/MGO/4-HNE, selenium enzymes get hammered. Birds seem to combine selenium enzymes with a lower-damage architecture:

less peroxide leakage
less PUFA chain damage
more antioxidant buffering
better NRF2 tone

So Sec–SeOH is less likely to be pushed into overoxidized/inactivated selenium states.

7. Michael adducts: birds probably produce fewer lipid-electrophile adducts

Michael acceptors like 4-HNE, acrolein, and quinones attack cysteine/selenocysteine:

Cys-S⁻ + 4-HNE → Cys-HNE adduct
Sec-Se⁻ + electrophile → Sec-electrophile adduct

The biggest source of endogenous Michael acceptors is lipid peroxidation. Since long-lived birds show lower lipid oxidative damage and have more peroxidation-resistant membranes, they likely generate fewer lipid-derived electrophiles. Comparative bird work found long-lived species have lower MDA, a lipid peroxidation marker. (PMC)

So for Michael adducts:

mammal strategy:
repair/detox after lipid electrophiles form

long-lived bird strategy:
make fewer lipid electrophiles in the first place

That is the superior strategy. Repair is nice. Not needing repair is nicer. Someone should tell human metabolism, but it is busy inventing diabetes complications.

8. Amadori products / glycation: birds are weirdly resistant despite high glucose

This is the really interesting one.

Birds often run blood glucose that would look alarming in mammals. A review notes that birds naturally have blood glucose nearly double that of similar-sized mammals and yet do not develop the same diabetes-like complications. (ScienceDirect)

A 2025 eLife comparative analysis across 88 bird species found that glucose correlates with albumin glycation, as expected, but the relationship is nonlinear: birds with higher glucose show relatively lower albumin glycation than expected, suggesting glycation resistance. (eLife)

So for Amadori chemistry:

mammal:
high glucose → Schiff base → Amadori → AGE → crosslink/inflammation

bird:
high glucose → less glycation than expected → slower AGE-like damage progression

This does not mean birds have no AGEs. It means their glycation burden is strangely decoupled from glucose compared with what mammalian intuition would predict.

Possible reasons include:

albumin/protein sequence less glycation-prone
higher antioxidant buffering
high urate
better dicarbonyl detox
lower lipid peroxidation / glycoxidation coupling
faster protein turnover in key compartments

The exact mechanism is still not settled, because naturally the organism that looks like a flying pinecone also has unsolved metabolic biochemistry.

9. MGO / glyoxal / dicarbonyl stress: probably better buffering, less propagation

MGO comes from glycolysis and glycation chemistry:

triose phosphates → methylglyoxal
MGO + Arg/Lys/Cys → adducts / AGEs

Birds should have a huge problem here because of high glucose. Yet songbird data suggest high glucose is not strongly coupled to oxidative lipid damage at macroevolutionary scale, and the authors argue birds evolved adaptations preventing glucose-induced oxidative stress. (The Company of Biologists)

So birds may not necessarily produce zero MGO. Instead, they likely prevent the MGO/glycation/oxidative loop from amplifying:

high glucose
  ↘
 MGO / glycation
  ↘
 ROS / lipid peroxidation
  ↘
 more aldehydes / Michael adducts / AGEs

Long-lived birds seem better at breaking that loop.

My compressed ranking: birds vs mammals

Damage/repair axis	Long-lived birds vs similar-sized mammals
Cys-Cys disulfide cycling	Likely better buffered; more reversible redox control
Cys–SOH sulfenic acid	Likely resolved faster, less overoxidation
Cys–SO₂H sulfinic acid	Probably less formation; repair not clearly superior
Cys–SO₃H sulfonic acid	Likely less accumulation because upstream oxidative load is lower
Met sulfoxide	Conserved repair; advantage probably lower damage load, not magic Msr
Sec–SeOH cycling	Uses same selenoprotein chemistry, likely under less overoxidative pressure
Michael adducts	Fewer lipid-derived electrophiles because less lipid peroxidation
Amadori/glycation	Surprisingly resistant relative to glucose burden
MGO/glyoxal stress	Probably better decoupled from oxidative/lipid damage loops
Lipid peroxidation	Major bird advantage
NRF2/antioxidant tone	Strong candidate advantage, especially Neoaves

The cleanest model

Long-lived mammals often solve aging by being large, slow, low-metabolic, or unusually stress-resistant. Long-lived birds solve it by being absurd:

high metabolism
high temperature
high glucose
high oxygen demand
but:
lower ROS leakage than expected
less peroxidizable membranes
high antioxidant buffering
constitutive cytoprotective response
glycation resistance

So relative to mammals, long-lived birds are not merely “better at repairing oxidized cysteine.” They are better at keeping redox chemistry in the reversible zone:

GOOD:
Cys-SH ⇄ Cys-SOH ⇄ Cys-S-S-Cys
Met ⇄ Met-SO
Sec-SeH ⇄ Sec-SeOH

BAD:
Cys-SO3H
protein-HNE adducts
AGE crosslinks
irreversible carbonylated proteins

The avian trick is preventing the good ladder from sliding into the bad ladder. Which is exactly what you’d want if you were a tiny hot-blooded aircraft with glucose levels that would make a mammalian endocrinologist reach for a clipboard and a sedative.