Cycle No. 06 · Quantitative
Does Turchin's secular cycle hold up?
Peter Turchin · Does it hold up?
Not testable on the record that exists — and that is the finding, not a dodge.
This page draws a wave around the peak year this site uses for Peter Turchin's cycle, up to today. It is not a forecast, and not evidence for or against the cycle.
The record this verdict is judged on, US top 1% wealth share (1913 onward), runs 111 years: 0.7 of the 3.0 full periods this site requires before it will run a test on a 150-year claim. Roughly 339 more years of that measurement would reach the floor.
This is not a verdict about this theory in particular: 0 of the 9 paired constructions on this site clear that floor. Long-cycle claims are hard to test because the records are short, not because the theorists are careless.
150-year sinusoid US top 1% wealth share (1913 onward): the record the verdict counts, drawn below on its own scale. A shape that looks alike is not a test.
~150-year US-specific secular cycle (Ages of Discord, 2016): elite overproduction → immiseration (stagnating mass living standards) → state breakdown → reconsolidation. His pre-industrial agrarian cycles in Secular Cycles run ~200–300 years; a separate ~50-year bigenerational cycle stacks on top
- Period
- 150 years
- Reference peak
- 2020
- Paired data
- Top 1% wealth share
- Judged on
- 1913 onward · why?
Peak calibration
Move the peak yourself: calibrate this cycle →
Center of Turchin's published forecast window for US instability peaking in the 2020s (Nature 2010, Ages of Discord 2016). The 150-year period is specific to his US-compressed grand cycle in Ages of Discord. This site draws only part of the one 150-year period around the 2020 anchor: from its 1945 trough up to the present. Repeated back, a 150-year wave from that anchor would put its prior peak at 1870 - close to the Civil War instability climax of ~1860 (curve height ≈ +0.91 at 1860, on a scale from −1 at a low to +1 at a peak) but ~90 years off from the Revolutionary War of ~1780, which it would plot near a trough (curve height ≈ −0.81 at 1780). Turchin's actual stated US instability climaxes (1780s, 1860s, 2020s) are not uniformly 150 years apart - gaps of ~80 years (1780s → 1860s) and ~160 years (1860s → 2020s) - so a strict 150-year sinusoid is a forced reduction of a non-uniform cycle. His pre-industrial agrarian secular cycles in Secular Cycles run 200–300 years and his separate bigenerational cycle is ~50 years.
Confidence classification: Quantitative — the period comes from statistical work on historical data. It grades the theorist's own evidence for the period; a paired data series is a separate comparison this site added. Every cycle on this site is drawn as at most one period of a pure sinusoid, cut at today where that period has not ended yet, built from one documented period and one documented reference peak, each taken from the theory or, where it gives none, chosen by this site — a deliberately naïve construction, so that disagreement between theories rather than parameter fitting is what you see. See about for why this site draws each cycle once, not as a repeating wave.
Where this curve plots its extrema
Computed from period 150 and reference peak 2020, over the part of its one period this site draws, up to today (1945–2026; the period has not ended yet). These are positions of this construction, not dates claimed by the theorist.
- Peaks
- 2020
- Troughs
- 1945
Paired data series
US Top 1% Wealth Share
% of household wealthShare of total household wealth held by the top 1% of US adults. The modern Saez–Zucman series begins 1913; pre-1913 points (1820, 1850, 1880, 1900, 1910) are spliced from earlier historical sources via OWID/WID and have wider standard errors
Why two labels: the “Paired data” line and section on this page, and the citation at the end, name the whole US Top 1% Wealth Share series, which the interactive chart draws from 1820. The verdict counts only the yearly record, which starts in 1913 with the Saez–Zucman series, and that is what the figure at the top of this page draws. Before 1913 there are just five points (1820, 1850, 1880, 1900 and 1910), rougher estimates from earlier historical sources that the interactive chart joins into one line. They are left out of that yearly record, which is why the figure at the top hatches 1820 to 1910 along with every other year before 1913. So the site measures the record's length from 1913, and would run any test on those yearly figures only.
Why this pairingThis site pairs US top-1% wealth share with Turchin's secular cycle as a proposed proxy for elite overproduction, the driver in his account. It measures wealth concentration, not elite numbers or instability, so it cannot by itself show that his cycle holds or that his 2020s forecast came true.
- Source
- WID · World Inequality Database, retrieved via Our World in Data. 1913–present from Saez & Zucman (2016) / DINA; pre-1913 decadal points (1820, 1850, 1880, 1900, 1910) are WID interpolations sourced from earlier US wealth-distribution literature, not from Saez–Zucman directly
- License
- CC BY 4.0
Spectral verdict
Insufficient data — no test possible · 0.7 of 3.0 required periods
The US top 1% wealth share (1913 onward) record spans 111 years — 0.7 of the 3.0 full periods this site requires before testing a 150-year claim. No test was run and no p-value exists: the honest verdict is that the record is too short to test the claim at all.
“Insufficient data” is an eligibility outcome under the site's pre-registered 3.0-period rule - the test is declined, not failed - and is not evidence for or against the theory.
This pairing has no p-value. Separately, this site's secondary cross-grid panel borrows a theory's period and sets it against a record that theory is not paired with, so none of its re-pairings is this theory's own claim. This page's record, US top 1% wealth share (1913 onward), was set against 1 other theory's period: Schlesinger Jr.'s 30 years (lowest p 0.103). That re-pairing did not reach p < 0.05 under either noise model. All 19 re-pairings, cell by cell →
Target period 150 years · Insufficient data — no test possible · 0.7 of 3.0 required periods
Swipe sideways for the whole figure
Wider than this window: use the arrows at its edges to see the rest, or click it to open it full size
No test was run: this record covers 0.7 of the 3.0 full periods the pre-registered test requires, so the spectrum in the figure is descriptive only. Had the record qualified, the test would be a harmonic regression at the exact stated period against an AR(1) red-noise null (99,999 bootstrap draws). Read the protocol under spectral testing on the methods page, or fetch the machine-readable verdicts.json.
Reuse this
Kooi, D. (2026). Sinusoidal History: Peter Turchin — secular cycles. https://sinusoidalhistory.com/cycles/turchin · DOI 10.5281/zenodo.21998618. Paired data series: US Top 1% Wealth Share (WID · World Inequality Database, retrieved via Our World in Data), CC BY 4.0.
Our code and the original chart files are MIT-licensed as our own work. The plotted data stay under their upstream terms, listed above: CC BY series carry their attribution requirement with them, and a series with no explicit license is shown here without any grant we can pass on. Reuse our figures and code with attribution; honour the data terms for the plotted series.
Open this cycle in the interactive chart to calibrate its peak and period against the data, or compare it with the other nine on one axis.