Cycle No. 06 · Quantitative
Peter Turchin — secular cycles
~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
Peter Turchin · Does it hold up?
Not testable on the record that exists — and that is the finding, not a dodge.
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.
By this page's curve, 2026 sits on the falling arm (cos +0.97). The next low falls around 2095, and the next high around 2170. That is a position of this construction, not the theorist's forecast. Every cycle in 2026 →
- Period
- 150 years
- Reference peak
- 2020
- Paired data
- Top 1% wealth share
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. With our 2020 anchor + period 150, the sinusoid's prior peak lands at 1870 - close to the Civil War instability climax of ~1860 (cos ≈ +0.91 at 1860) but ~90 years off from the Revolutionary War of ~1780, which our sinusoid plots near a trough (cos ≈ −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 a pure sinusoid built from the theory's stated period and one documented reference peak — a deliberately naïve construction, so that disagreement between theories rather than parameter fitting is what you see. See about for why nearly every cycle peaks near the present.
Where this curve plots its extrema
Computed from period 150 and reference peak 2020, across the site's default window (1600–2050). These are positions of this construction, not dates claimed by the theorist.
- Peaks
- 1720 · 1870 · 2020
- Troughs
- 1645 · 1795 · 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 this pairingDirect proxy for Turchin's elite-overproduction driver - when wealth concentrates, elite competition intensifies and instability follows.
- 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.
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. Before 1913 there are just five points (1820, 1850, 1880, 1900 and 1910), rougher estimates from earlier historical sources that the chart joins into one line. So the site measures the record's length from 1913, and would run any test on those yearly figures only.
“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.
Target period 150 years · Insufficient data — no test possible · 0.7 of 3.0 required periods
Swipe sideways for the whole figure
Scroll sideways for the whole figure, 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.